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Annotation of OpenXM_contrib2/asir2018/engine/Fgfs.c, Revision 1.1

1.1     ! noro        1: /* $OpenXM$ */
        !             2:
        !             3: #include "ca.h"
        !             4:
        !             5: void cont_pp_mv_sf(VL vl,VL rvl,P p,P *c,P *pp);
        !             6: void gcdsf_main(VL vl,P *pa,int m,P *r);
        !             7: void ugcdsf(P *pa,int m,P *r);
        !             8: void head_monomial(VL vl,V v,P p,P *coef,P *term);
        !             9: void sqfrsfmain(VL vl,P f,DCP *dcp);
        !            10: void pthrootsf(P f,Z m,P *r);
        !            11: void partial_sqfrsf(VL vl,V v,P f,P *r,DCP *dcp);
        !            12: void gcdsf(VL vl,P *pa,int k,P *r);
        !            13: void mfctrsfmain(VL vl, P f, DCP *dcp);
        !            14: void next_evaluation_point(int *mev,int n);
        !            15: void estimatelc_sf(VL vl,VL rvl,P c,DCP dc,int *mev,P *lcp);
        !            16: void mfctrsf_hensel(VL vl,VL rvl,P f,P pp0,P u0,P v0,P lcu,P lcv,int *mev,P *up);
        !            17: void substvp_sf(VL vl,VL rvl,P f,int *mev,P *r);
        !            18: void shift_sf(VL vl, VL rvl, P f, int *mev, int sgn, P *r);
        !            19: void adjust_coef_sf(VL vl,VL rvl,P lcu,P u0,int *mev,P *r);
        !            20: void extended_gcd_modyk(P u0,P v0,V x,V y,int dy,P *cu,P *cv);
        !            21: void poly_to_gfsn_poly(VL vl,P f,V v,P *r);
        !            22: void gfsn_poly_to_poly(VL vl,P f,V v,P *r);
        !            23: void poly_to_gfsn_poly_main(P f,V v,P *r);
        !            24: void gfsn_poly_to_poly_main(P f,V v,P *r);
        !            25: void gfsn_univariate_to_sfbm(P f,int dy,BM *r);
        !            26: void sfbm_to_gfsn_univariate(BM f,V x,V y,P *r);
        !            27:
        !            28: void monomialfctr_sf(VL vl,P p,P *pr,DCP *dcp)
        !            29: {
        !            30:   VL nvl,avl;
        !            31:   Z d;
        !            32:   P f,t,s;
        !            33:   DCP dc0,dc;
        !            34:   Obj obj;
        !            35:
        !            36:   clctv(vl,p,&nvl);
        !            37:   for ( dc0 = 0, avl = nvl, f = p; avl; avl = NEXT(avl) ) {
        !            38:     getmindeg(avl->v,f,&d);
        !            39:     if ( d ) {
        !            40:       MKV(avl->v,t);
        !            41:       simp_ff((Obj)t,&obj); t = (P)obj;
        !            42:       NEXTDC(dc0,dc); DEG(dc) = d; COEF(dc) = t;
        !            43:       pwrp(vl,t,d,&s); divsp(vl,f,s,&t); f = t;
        !            44:     }
        !            45:   }
        !            46:   if ( dc0 )
        !            47:     NEXT(dc) = 0;
        !            48:   *pr = f; *dcp = dc0;
        !            49: }
        !            50:
        !            51: void lex_lc(P f,P *c)
        !            52: {
        !            53:   if ( !f || NUM(f) )
        !            54:     *c = f;
        !            55:   else
        !            56:     lex_lc(COEF(DC(f)),c);
        !            57: }
        !            58:
        !            59: DCP append_dc(DCP dc,DCP dct)
        !            60: {
        !            61:   DCP dcs;
        !            62:
        !            63:   if ( !dc )
        !            64:     return dct;
        !            65:   else {
        !            66:     for ( dcs = dc; NEXT(dcs); dcs = NEXT(dcs) );
        !            67:     NEXT (dcs) = dct;
        !            68:     return dc;
        !            69:   }
        !            70: }
        !            71:
        !            72: void sqfrsf(VL vl, P f, DCP *dcp)
        !            73: {
        !            74:   DCP dc,dct;
        !            75:   Obj obj;
        !            76:   P t,s,c,cont;
        !            77:   VL tvl,onevl;
        !            78:
        !            79:   simp_ff((Obj)f,&obj); f = (P)obj;
        !            80:   lex_lc(f,&c); divsp(vl,f,c,&t); f = t;
        !            81:   monomialfctr_sf(vl,f,&t,&dc); f = t;
        !            82:   clctv(vl,f,&tvl); vl = tvl;
        !            83:   NEWVL(onevl); NEXT(onevl)=0;
        !            84:   if ( !vl )
        !            85:     ;
        !            86:   else if ( !NEXT(vl) ) {
        !            87:     sfusqfr(f,&dct);
        !            88:     dc = append_dc(dc,NEXT(dct));
        !            89:   } else {
        !            90:     t = f;
        !            91:     for ( tvl = vl; tvl; tvl = NEXT(tvl) ) {
        !            92:       onevl->v = tvl->v;
        !            93:       cont_pp_mv_sf(vl,onevl,t,&cont,&s); t = s;
        !            94:       sqfrsf(vl,cont,&dct);
        !            95:       dc = append_dc(dc,NEXT(dct));
        !            96:     }
        !            97:     sqfrsfmain(vl,t,&dct);
        !            98:     dc = append_dc(dc,dct);
        !            99:   }
        !           100:   NEWDC(dct); DEG(dct) = ONE; COEF(dct) = (P)c; NEXT(dct) = dc;
        !           101:   *dcp = dct;
        !           102: }
        !           103:
        !           104: void sqfrsfmain(VL vl,P f,DCP *dcp)
        !           105: {
        !           106:   VL tvl;
        !           107:   DCP dc,dct,dcs;
        !           108:   P t,s;
        !           109:   Z m,m1;
        !           110:   V v;
        !           111:
        !           112:   clctv(vl,f,&tvl); vl = tvl;
        !           113:   dc = 0;
        !           114:   t = f;
        !           115:   for ( tvl = vl; tvl; tvl = NEXT(tvl) ) {
        !           116:     v = tvl->v;
        !           117:     partial_sqfrsf(vl,v,t,&s,&dct); t = s;
        !           118:     dc = append_dc(dc,dct);
        !           119:   }
        !           120:   if ( !NUM(t) ) {
        !           121:     STOQ(characteristic_sf(),m);
        !           122:     pthrootsf(t,m,&s);
        !           123:     sqfrsfmain(vl,s,&dct);
        !           124:     for ( dcs = dct; dcs; dcs = NEXT(dcs) ) {
        !           125:       mulz(DEG(dcs),m,&m1); DEG(dcs) = m1;
        !           126:     }
        !           127:     dc = append_dc(dc,dct);
        !           128:   }
        !           129:   *dcp = dc;
        !           130: }
        !           131:
        !           132: void pthrootsf(P f,Z m,P *r)
        !           133: {
        !           134:   DCP dc,dc0,dct;
        !           135:   Z qn,rn;
        !           136:
        !           137:   if ( NUM(f) )
        !           138:     pthrootgfs((GFS)f,(GFS *)r);
        !           139:   else {
        !           140:     dc = DC(f);
        !           141:     dc0 = 0;
        !           142:     for ( dc0 = 0; dc; dc = NEXT(dc) ) {
        !           143:       NEXTDC(dc0,dct);
        !           144:       pthrootsf(COEF(dc),m,&COEF(dct));
        !           145:       if ( DEG(dc) ) {
        !           146:         divqrz(DEG(dc),m,&qn,&rn);
        !           147:         if ( rn )
        !           148:           error("pthrootsf : cannot happen");
        !           149:         DEG(dct) = qn;
        !           150:       } else
        !           151:         DEG(dct) = 0;
        !           152:     }
        !           153:     NEXT(dct) = 0;
        !           154:     MKP(VR(f),dc0,*r);
        !           155:   }
        !           156: }
        !           157:
        !           158: void partial_sqfrsf(VL vl,V v,P f,P *r,DCP *dcp)
        !           159: {
        !           160:   P ps[2];
        !           161:   DCP dc0,dc;
        !           162:   int m;
        !           163:   P t,flat,flat1,g,df,q;
        !           164:
        !           165:   diffp(vl,f,v,&df);
        !           166:   if ( !df ) {
        !           167:     *dcp = 0;
        !           168:     *r = f;
        !           169:     return;
        !           170:   }
        !           171:   ps[0] = f; ps[1] = df;
        !           172:   gcdsf(vl,ps,2,&g);
        !           173:   divsp(vl,f,g,&flat);
        !           174:   m = 0;
        !           175:   t = f;
        !           176:   dc0 = 0;
        !           177:   while ( !NUM(flat) ) {
        !           178:     while ( divtp(vl,t,flat,&q) ) {
        !           179:       t = q; m++;
        !           180:     }
        !           181:     ps[0] = t; ps[1] = flat;
        !           182:     gcdsf(vl,ps,2,&flat1);
        !           183:     divsp(vl,flat,flat1,&g);
        !           184:     flat = flat1;
        !           185:     NEXTDC(dc0,dc);
        !           186:     COEF(dc) = g;
        !           187:     STOQ(m,DEG(dc));
        !           188:   }
        !           189:   NEXT(dc) = 0;
        !           190:   *dcp = dc0;
        !           191:   *r = t;
        !           192: }
        !           193:
        !           194: void gcdsf(VL vl,P *pa,int k,P *r)
        !           195: {
        !           196:   P *ps,*pl,*pm;
        !           197:   P **cp;
        !           198:   int *cn;
        !           199:   DCP *ml;
        !           200:   Obj obj;
        !           201:   int i,j,l,m;
        !           202:   P mg,mgsf,t;
        !           203:   VL avl,nvl,tvl,svl;
        !           204:
        !           205:   ps = (P *)ALLOCA(k*sizeof(P));
        !           206:   for ( i = 0, m = 0; i < k; i++ ) {
        !           207:     simp_ff((Obj)pa[i],&obj);
        !           208:     if ( obj )
        !           209:       ps[m++] = (P)obj;
        !           210:   }
        !           211:   if ( !m ) {
        !           212:     *r = 0;
        !           213:     return;
        !           214:   }
        !           215:   if ( m == 1 ) {
        !           216:     *r = ps[0];
        !           217:     return;
        !           218:   }
        !           219:   pl = (P *)ALLOCA(m*sizeof(P));
        !           220:   ml = (DCP *)ALLOCA(m*sizeof(DCP));
        !           221:   for ( i = 0; i < m; i++ )
        !           222:     monomialfctr(vl,ps[i],&pl[i],&ml[i]);
        !           223:   gcdmonomial(vl,ml,m,&mg); simp_ff((Obj)mg,&obj); mgsf = (P)obj;
        !           224:   for ( i = 0, nvl = vl, avl = 0; nvl && i < m; i++ ) {
        !           225:     clctv(vl,pl[i],&tvl);
        !           226:     intersectv(nvl,tvl,&svl); nvl = svl;
        !           227:     mergev(vl,avl,tvl,&svl); avl = svl;
        !           228:   }
        !           229:   if ( !nvl ) {
        !           230:     *r = mgsf;
        !           231:     return;
        !           232:   }
        !           233:   if ( !NEXT(avl) ) {
        !           234:     ugcdsf(pl,m,&t);
        !           235:     mulp(vl,mgsf,t,r);
        !           236:     return;
        !           237:   }
        !           238:   for ( tvl = nvl, i = 0; tvl; tvl = NEXT(tvl), i++ );
        !           239:   for ( tvl = avl, j = 0; tvl; tvl = NEXT(tvl), j++ );
        !           240:   if ( i == j ) {
        !           241:     /* all the pl[i]'s have the same variables */
        !           242:     gcdsf_main(avl,pl,m,&t);
        !           243:   } else {
        !           244:     cp = (P **)ALLOCA(m*sizeof(P *));
        !           245:     cn = (int *)ALLOCA(m*sizeof(int));
        !           246:     for ( i = 0; i < m; i++ ) {
        !           247:       cp[i] = (P *)ALLOCA(lengthp(pl[i])*sizeof(P));
        !           248:       cn[i] = pcoef(vl,nvl,pl[i],cp[i]);
        !           249:     }
        !           250:     for ( i = j = 0; i < m; i++ )
        !           251:       j += cn[i];
        !           252:     pm = (P *)ALLOCA(j*sizeof(P));
        !           253:     for ( i = l = 0; i < m; i++ )
        !           254:       for ( j = 0; j < cn[i]; j++ )
        !           255:         pm[l++] = cp[i][j];
        !           256:     gcdsf(vl,pm,l,&t);
        !           257:   }
        !           258:   mulp(vl,mgsf,t,r);
        !           259: }
        !           260:
        !           261: /* univariate gcd */
        !           262:
        !           263: void ugcdsf(P *pa,int m,P *r)
        !           264: {
        !           265:   P *ps;
        !           266:   int i;
        !           267:   UM w1,w2,w3,w;
        !           268:   int d;
        !           269:   V v;
        !           270:
        !           271:   if ( m == 1 ) {
        !           272:     *r = pa[0];
        !           273:     return;
        !           274:   }
        !           275:   for ( i = 0; i < m; i++ )
        !           276:     if ( NUM(pa[i]) ) {
        !           277:       itogfs(1,(GFS *)r);
        !           278:       return;
        !           279:     }
        !           280:   ps = (P *)ALLOCA(m*sizeof(P));
        !           281:   sort_by_deg(m,pa,ps);
        !           282:   v = VR(ps[m-1]);
        !           283:   d = getdeg(v,ps[m-1]);
        !           284:   w1 = W_UMALLOC(d);
        !           285:   w2 = W_UMALLOC(d);
        !           286:   w3 = W_UMALLOC(d);
        !           287:   ptosfum(ps[0],w1);
        !           288:   for ( i = 1; i < m; i++ ) {
        !           289:     ptosfum(ps[i],w2);
        !           290:     gcdsfum(w1,w2,w3);
        !           291:     w = w1; w1 = w3; w3 = w;
        !           292:     if ( !DEG(w1) ) {
        !           293:       itogfs(1,(GFS *)r);
        !           294:       return;
        !           295:     }
        !           296:   }
        !           297:   sfumtop(v,w1,r);
        !           298: }
        !           299:
        !           300: /* deg(HT(p),v), where p is considered as distributed poly over F[v] */
        !           301: int gethdeg(VL vl,V v,P p)
        !           302: {
        !           303:   DCP dc;
        !           304:   Z dmax;
        !           305:   P cmax;
        !           306:
        !           307:   if ( !p )
        !           308:     return -1;
        !           309:   else if ( NUM(p) )
        !           310:     return 0;
        !           311:   else if ( VR(p) != v )
        !           312:     /* HT(p) = HT(lc(p))*x^D */
        !           313:     return gethdeg(vl,v,COEF(DC(p)));
        !           314:   else {
        !           315:     /* VR(p) = v */
        !           316:     dc = DC(p); dmax = DEG(dc); cmax = COEF(dc);
        !           317:     for ( dc = NEXT(dc); dc; dc = NEXT(dc) )
        !           318:       if ( compp(vl,COEF(dc),cmax) > 0 ) {
        !           319:         dmax = DEG(dc); cmax = COEF(dc);
        !           320:       }
        !           321:     return QTOS(dmax);
        !           322:   }
        !           323: }
        !           324:
        !           325: /* all the pa[i]'s have the same variables (=vl) */
        !           326:
        !           327: void gcdsf_main(VL vl,P *pa,int m,P *r)
        !           328: {
        !           329:   int nv,i,i0,imin,d,d0,d1,d2,dmin,index;
        !           330:   V v,v0,vmin;
        !           331:   VL tvl,nvl,rvl,nvl0,rvl0;
        !           332:   P *pc, *ps, *ph,*lps;
        !           333:   P x,t,cont,hg,g,hm,mod,s;
        !           334:   P hge,ge,ce,he,u,cof1e,mode,mod1,adj,cof1,coadj,q;
        !           335:   GFS sf;
        !           336:
        !           337:   for ( nv = 0, tvl = vl; tvl; tvl = NEXT(tvl), nv++);
        !           338:   if ( nv == 1 ) {
        !           339:     ugcdsf(pa,m,r);
        !           340:     return;
        !           341:   }
        !           342:   /* find v s.t. min(deg(pa[i],v)+gethdeg(pa[i],v)) is minimal */
        !           343:   tvl = vl;
        !           344:   do {
        !           345:     v = tvl->v;
        !           346:     i = 0;
        !           347:     do {
        !           348:       d = getdeg(v,pa[i])+gethdeg(vl,v,pa[i]);
        !           349:       if ( i == 0 || (d < d0) ) {
        !           350:         d0 = d; i0 = i; v0 = v;
        !           351:       }
        !           352:     } while ( ++i < m );
        !           353:     if ( tvl == vl || (d0 < dmin) ) {
        !           354:       dmin = d0; imin = i0; vmin = v0;
        !           355:     }
        !           356:   } while ( (tvl = NEXT(tvl)) != 0 );
        !           357:
        !           358:   /* reorder variables so that vmin is the last variable */
        !           359:   for ( nvl0 = 0, rvl0 = 0, tvl = vl; tvl; tvl = NEXT(tvl) )
        !           360:     if ( tvl->v != vmin ) {
        !           361:       NEXTVL(nvl0,nvl); nvl->v = tvl->v;
        !           362:       NEXTVL(rvl0,rvl); rvl->v = tvl->v;
        !           363:     }
        !           364:   /* rvl = remaining variables */
        !           365:   NEXT(rvl) = 0; rvl = rvl0;
        !           366:   /* nvl = ...,vmin */
        !           367:   NEXTVL(nvl0,nvl); nvl->v = vmin; NEXT(nvl) = 0; nvl = nvl0;
        !           368:   MKV(vmin,x);
        !           369:
        !           370:   /* for content and primitive part */
        !           371:   pc = (P *)ALLOCA(m*sizeof(P));
        !           372:   ps = (P *)ALLOCA(m*sizeof(P));
        !           373:   ph = (P *)ALLOCA(m*sizeof(P));
        !           374:   /* separate the contents */
        !           375:   for ( i = 0; i < m; i++ ) {
        !           376:     reorderp(nvl,vl,pa[i],&t);
        !           377:     cont_pp_mv_sf(nvl,rvl,t,&pc[i],&ps[i]);
        !           378:     head_monomial(nvl,vmin,ps[i],&ph[i],&t);
        !           379:   }
        !           380:   ugcdsf(pc,m,&cont);
        !           381:   ugcdsf(ph,m,&hg);
        !           382:
        !           383:   /* for hg*pp (used in check phase) */
        !           384:   lps = (P *)ALLOCA(m*sizeof(P));
        !           385:   for ( i = 0; i < m; i++ )
        !           386:     mulp(nvl,hg,ps[i],&lps[i]);
        !           387:
        !           388:   while ( 1 ) {
        !           389:     g = 0;
        !           390:     cof1 = 0;
        !           391:     hm = 0;
        !           392:     itogfs(1,(GFS *)&mod);
        !           393:     index = 0;
        !           394:     for ( index = 0; getdeg(vmin,mod) <= d+1; index++ ) {
        !           395:       /* evaluation pt */
        !           396:       indextogfs(index,(GFS *)&s);
        !           397:       substp(nvl,hg,vmin,s,&hge);
        !           398:       if ( !hge )
        !           399:         continue;
        !           400:       for ( i = 0; i < m; i++ )
        !           401:         substp(nvl,ps[i],vmin,s,&ph[i]);
        !           402:       /* ge = GCD(ps[0]|x=s,...,ps[m-1]|x=s) */
        !           403:       gcdsf(nvl,ph,m,&ge);
        !           404:       head_monomial(nvl,vmin,ge,&ce,&he);
        !           405:       if ( NUM(he) ) {
        !           406:         *r = cont;
        !           407:         return;
        !           408:       }
        !           409:       divgfs((GFS)hge,(GFS)ce,&sf); t = (P)sf;
        !           410:       mulp(nvl,t,ge,&u); ge = u;
        !           411:       divsp(nvl,ph[imin],ge,&t); mulp(nvl,hge,t,&cof1e);
        !           412:       /* hm=0 : reset; he==hm : lucky */
        !           413:       if ( !hm || !compp(nvl,he,hm) ) {
        !           414:         substp(nvl,mod,vmin,s,&mode); divsp(nvl,mod,mode,&mod1);
        !           415:         /* adj = mod/(mod|x=s)*(ge-g|x=s) */
        !           416:         substp(nvl,g,vmin,s,&t);
        !           417:         subp(nvl,ge,t,&u); mulp(nvl,mod1,u,&adj);
        !           418:         /* coadj = mod/(mod|vmin=s)*(cof1e-cof1e|vmin=s) */
        !           419:         substp(nvl,cof1,vmin,s,&t);
        !           420:         subp(nvl,cof1e,t,&u); mulp(nvl,mod1,u,&coadj);
        !           421:         if ( !adj ) {
        !           422:           /* adj == gcd ? */
        !           423:           for ( i = 0; i < m; i++ )
        !           424:             if ( !divtp(nvl,lps[i],g,&t) )
        !           425:               break;
        !           426:           if ( i == m ) {
        !           427:             cont_pp_mv_sf(nvl,rvl,g,&t,&u);
        !           428:             mulp(nvl,cont,u,&t);
        !           429:             reorderp(vl,nvl,t,r);
        !           430:             return;
        !           431:           }
        !           432:         } else if ( !coadj ) {
        !           433:           /* ps[imin]/coadj == gcd ? */
        !           434:           if ( divtp(nvl,lps[imin],cof1,&q) ) {
        !           435:             for ( i = 0; i < m; i++ )
        !           436:               if ( !divtp(nvl,lps[i],q,&t) )
        !           437:                 break;
        !           438:             if ( i == m ) {
        !           439:               cont_pp_mv_sf(nvl,rvl,q,&t,&u);
        !           440:               mulp(nvl,cont,u,&t);
        !           441:               reorderp(vl,nvl,t,r);
        !           442:               return;
        !           443:             }
        !           444:           }
        !           445:         }
        !           446:         addp(nvl,g,adj,&t); g = t;
        !           447:         addp(nvl,cof1,coadj,&t); cof1 = t;
        !           448:         subp(nvl,x,s,&t); mulp(nvl,mod,t,&u); mod = u;
        !           449:         hm = he;
        !           450:       } else {
        !           451:         d1 = homdeg(hm); d2 = homdeg(he);
        !           452:         if ( d1 < d2 ) /* we use current hm */
        !           453:           continue;
        !           454:         else if ( d1 > d2 ) {
        !           455:           /* use he */
        !           456:           g = ge;
        !           457:           cof1 = cof1e;
        !           458:           hm = he;
        !           459:           subp(nvl,x,s,&mod);
        !           460:         } else {
        !           461:           /* d1==d2, but hm!=he => both are unlucky */
        !           462:           g = 0;
        !           463:           cof1 = 0;
        !           464:           itogfs(1,(GFS *)&mod);
        !           465:         }
        !           466:       }
        !           467:     }
        !           468:   }
        !           469: }
        !           470:
        !           471: void head_monomial(VL vl,V v,P p,P *coef,P *term)
        !           472: {
        !           473:   P t,s,u;
        !           474:   DCP dc;
        !           475:   GFS one;
        !           476:
        !           477:   itogfs(1,&one);
        !           478:   t = (P)one;
        !           479:   while ( 1 ) {
        !           480:     if ( NUM(p) || VR(p) == v ) {
        !           481:       *coef = p;
        !           482:       *term = t;
        !           483:       return;
        !           484:     } else {
        !           485:       NEWDC(dc);
        !           486:       COEF(dc) = (P)one; DEG(dc) = DEG(DC(p));
        !           487:       MKP(VR(p),dc,s);
        !           488:       mulp(vl,t,s,&u); t = u;
        !           489:       p = COEF(DC(p));
        !           490:     }
        !           491:   }
        !           492: }
        !           493:
        !           494: void cont_pp_mv_sf(VL vl,VL rvl,P p,P *c,P *pp)
        !           495: {
        !           496:   DP dp;
        !           497:   MP t;
        !           498:   int i,m;
        !           499:   P *ps;
        !           500:   struct order_spec *spec, *currentspec;
        !           501:   extern struct order_spec *dp_current_spec;
        !           502:
        !           503:   currentspec = dp_current_spec;
        !           504:   create_order_spec(0,0,&spec);
        !           505:   initd(spec);
        !           506:   ptod(vl,rvl,p,&dp);
        !           507:   for ( t = BDY(dp), m = 0; t; t = NEXT(t), m++ );
        !           508:   ps = (P *)ALLOCA(m*sizeof(P));
        !           509:   for ( t = BDY(dp), i = 0; t; t = NEXT(t), i++ )
        !           510:     ps[i] = (P)C(t);
        !           511:   gcdsf(vl,ps,m,c);
        !           512:   divsp(vl,p,*c,pp);
        !           513:   initd(currentspec);
        !           514: }
        !           515:
        !           516: void mfctrsf(VL vl, P f, DCP *dcp)
        !           517: {
        !           518:   DCP dc0,dc,dct,dcs,dcr;
        !           519:   Obj obj;
        !           520:
        !           521:   simp_ff((Obj)f,&obj); f = (P)obj;
        !           522:   sqfrsf(vl,f,&dct);
        !           523:   dc = dc0 = dct; dct = NEXT(dct); NEXT(dc) = 0;
        !           524:   for ( ; dct; dct = NEXT(dct) ) {
        !           525:     mfctrsfmain(vl,COEF(dct),&dcs);
        !           526:     for ( dcr = dcs; dcr; dcr = NEXT(dcr) )
        !           527:       DEG(dcr) = DEG(dct);
        !           528:     for ( ; NEXT(dc); dc = NEXT(dc) );
        !           529:     NEXT(dc) = dcs;
        !           530:   }
        !           531:   *dcp = dc0;
        !           532: }
        !           533:
        !           534: /* f : sqfr, non const */
        !           535:
        !           536: void mfctrsfmain(VL vl, P f, DCP *dcp)
        !           537: {
        !           538:   VL tvl,nvl,rvl;
        !           539:   DCP dc,dc0,dc1,dc2,dct,lcfdc,dcs;
        !           540:   int imin,inext,i,j,n,k,np;
        !           541:   int *da;
        !           542:   V vx,vy;
        !           543:   V *va;
        !           544:   P *l,*tl;
        !           545:   P gcd,g,df,dfmin;
        !           546:   P pa[2];
        !           547:   P f0,pp0,spp0,c,c0,x,y,u,v,lcf,lcu,lcv,u0,v0,t,s;
        !           548:   P ype,yme,fin;
        !           549:   GFS ev,evy;
        !           550:   P *fp0;
        !           551:   int *mev,*win;
        !           552:
        !           553:   clctv(vl,f,&tvl); vl = tvl;
        !           554:   if ( !vl )
        !           555:     error("mfctrsfmain : cannot happen");
        !           556:   if ( !NEXT(vl) ) {
        !           557:     /* univariate */
        !           558:     ufctrsf(f,&dc);
        !           559:     /* remove lc */
        !           560:     *dcp = NEXT(dc);
        !           561:     return;
        !           562:   }
        !           563:   for ( n = 0, tvl = vl; tvl; tvl = NEXT(tvl), n++ );
        !           564:   va = (V *)ALLOCA(n*sizeof(V));
        !           565:   da = (int *)ALLOCA(n*sizeof(int));
        !           566:   /* find v s.t. diff(f,v) is nonzero and deg(f,v) is minimal */
        !           567:   imin = -1;
        !           568:   for ( i = 0, tvl = vl; i < n; tvl = NEXT(tvl), i++ ) {
        !           569:     va[i] = tvl->v;
        !           570:     da[i] = getdeg(va[i],f);
        !           571:     diffp(vl,f,va[i],&df);
        !           572:     if ( !df )
        !           573:       continue;
        !           574:     if ( imin < 0 || da[i] < da[imin] ) {
        !           575:       dfmin = df;
        !           576:       imin = i;
        !           577:     }
        !           578:   }
        !           579:   /* find v1 neq v s.t. deg(f,v) is minimal */
        !           580:   inext = -1;
        !           581:   for ( i = 0; i < n; i++ ) {
        !           582:     if ( i == imin )
        !           583:       continue;
        !           584:     if ( inext < 0 || da[i] < da[inext] )
        !           585:       inext = i;
        !           586:   }
        !           587:   pa[0] = f;
        !           588:   pa[1] = dfmin;
        !           589:   gcdsf(vl,pa,2,&gcd);
        !           590:   if ( !NUM(gcd) ) {
        !           591:     /* f = gcd * f/gcd */
        !           592:     mfctrsfmain(vl,gcd,&dc1);
        !           593:     divsp(vl,f,gcd,&g);
        !           594:     mfctrsfmain(vl,g,&dc2);
        !           595:     for ( dct = dc1; NEXT(dct); dct = NEXT(dct) );
        !           596:     NEXT(dct) = dc2;
        !           597:     *dcp = dc1;
        !           598:     return;
        !           599:   }
        !           600:   /* create vl s.t. vl[0] = va[imin], vl[1] = va[inext] */
        !           601:   nvl = 0;
        !           602:   NEXTVL(nvl,tvl); tvl->v = va[imin];
        !           603:   NEXTVL(nvl,tvl); tvl->v = va[inext];
        !           604:   for ( i = 0; i < n; i++ ) {
        !           605:     if ( i == imin || i == inext )
        !           606:       continue;
        !           607:     NEXTVL(nvl,tvl); tvl->v = va[i];
        !           608:   }
        !           609:   NEXT(tvl) = 0;
        !           610:
        !           611:   fin = f;
        !           612:   reorderp(nvl,vl,f,&g); f = g;
        !           613:   vx = nvl->v;
        !           614:   vy = NEXT(nvl)->v;
        !           615:   MKV(vx,x);
        !           616:   MKV(vy,y);
        !           617:   /* remaining variables */
        !           618:   rvl = NEXT(NEXT(nvl));
        !           619:   if ( !rvl ) {
        !           620:     /* bivariate */
        !           621:     sfbfctr(f,vx,vy,getdeg(vx,f),&dc1);
        !           622:     for ( dc0 = 0; dc1; dc1 = NEXT(dc1) ) {
        !           623:       NEXTDC(dc0,dc);
        !           624:       DEG(dc) = ONE;
        !           625:       reorderp(vl,nvl,COEF(dc1),&COEF(dc));
        !           626:     }
        !           627:     NEXT(dc) = 0;
        !           628:     *dcp = dc0;
        !           629:     return;
        !           630:   }
        !           631:   /* n >= 3;  nvl = (vx,vy,X) */
        !           632:   /* find good evaluation pt for X */
        !           633:   mev = (int *)CALLOC(n-2,sizeof(int));
        !           634:   while ( 1 ) {
        !           635:     /* lcf(mev)=0 => invalid */
        !           636:     substvp_sf(nvl,rvl,COEF(DC(f)),mev,&t);
        !           637:     if ( t ) {
        !           638:       substvp_sf(nvl,rvl,f,mev,&f0);
        !           639:       pa[0] = f0;
        !           640:       diffp(nvl,f0,vx,&pa[1]);
        !           641:       if ( pa[1] ) {
        !           642:         gcdsf(nvl,pa,2,&gcd);
        !           643:       /* XXX maybe we have to accept the case where gcd is a poly of y */
        !           644:         if ( NUM(gcd) )
        !           645:           break;
        !           646:       }
        !           647:     }
        !           648:     /* XXX if generated indices exceed q of GF(q) => error in indextogfs */
        !           649:     next_evaluation_point(mev,n-2);
        !           650:   }
        !           651:   /* f0 = f(x,y,mev) */
        !           652:   /* separate content; f0 may have the content wrt x */
        !           653:   cont_pp_sfp(nvl,f0,&c0,&pp0);
        !           654:
        !           655:   /* factorize pp0; pp0 = pp0(x,y+evy) = prod dc */
        !           656:   sfbfctr_shift(pp0,vx,vy,getdeg(vx,pp0),&evy,&spp0,&dc); pp0 = spp0;
        !           657:
        !           658:   if ( !NEXT(dc) ) {
        !           659:     /* f is irreducible */
        !           660:     NEWDC(dc); DEG(dc) = ONE; COEF(dc) = fin; NEXT(dc) = 0;
        !           661:     *dcp = dc;
        !           662:     return;
        !           663:   }
        !           664:   /* ype = y+evy, yme = y-evy */
        !           665:   addp(nvl,y,(P)evy,&ype); subp(nvl,y,(P)evy,&yme);
        !           666:
        !           667:   /* shift c0; c0 <- c0(y+evy) */
        !           668:   substp(nvl,c0,vy,ype,&s); c0 = s;
        !           669:
        !           670:   /* shift f; f <- f(y+evy) */
        !           671:   substp(nvl,f,vy,ype,&s); f = s;
        !           672:
        !           673:   /* now f(x,0,mev) = c0 * prod dc */
        !           674:
        !           675:   /* factorize lc_x(f) */
        !           676:   lcf = COEF(DC(f));
        !           677:   mfctrsf(nvl,lcf,&dct);
        !           678:   /* skip the first element (= a number) */
        !           679:   lcfdc = NEXT(dct);
        !           680:
        !           681:   /* np = number of bivariate factors */
        !           682:   for ( np = 0, dct = dc; dct; dct = NEXT(dct), np++ );
        !           683:   fp0 = (P *)ALLOCA((np+1)*sizeof(P));
        !           684:   for ( i = 0, dct = dc; i < np; dct = NEXT(dct), i++ )
        !           685:     fp0[i] = COEF(dct);
        !           686:   fp0[np] = 0;
        !           687:   l = tl = (P *)ALLOCA((np+1)*sizeof(P));
        !           688:   win = W_ALLOC(np+1);
        !           689:
        !           690:   for ( k = 1, win[0] = 1, --np; ; ) {
        !           691:     itogfs(1,(GFS *)&u0);
        !           692:     /* u0 = product of selected factors */
        !           693:     for ( i = 0; i < k; i++ ) {
        !           694:       mulp(nvl,u0,fp0[win[i]],&t); u0 = t;
        !           695:     }
        !           696:     /* we have to consider the content */
        !           697:     /* f0 = c0*u0*v0 */
        !           698:     mulp(nvl,LC(u0),c0,&c); estimatelc_sf(nvl,rvl,c,lcfdc,mev,&lcu);
        !           699:     divsp(nvl,pp0,u0,&v0);
        !           700:     mulp(nvl,LC(v0),c0,&c); estimatelc_sf(nvl,rvl,c,lcfdc,mev,&lcv);
        !           701:     mfctrsf_hensel(nvl,rvl,f,pp0,u0,v0,lcu,lcv,mev,&u);
        !           702:     if ( u ) {
        !           703:       /* save the factor */
        !           704:       reorderp(vl,nvl,u,&t);
        !           705:       /* y -> y-evy */
        !           706:       substp(vl,t,vy,yme,tl++);
        !           707:
        !           708:       /* update f,pp0 */
        !           709:       divsp(nvl,f,u,&t); f = t;
        !           710:       divsp(nvl,pp0,u0,&t); pp0 = t;
        !           711:       /* update win, fp0 */
        !           712:       for ( i = 0; i < k-1; i++ )
        !           713:       for ( j = win[i]+1; j < win[i+1]; j++ )
        !           714:         fp0[j-i-1] = fp0[j];
        !           715:       for ( j = win[k-1]+1; j <= np; j++ )
        !           716:           fp0[j-k] = fp0[j];
        !           717:       if ( ( np -= k ) < k ) break;
        !           718:       if ( np-win[0]+1 < k )
        !           719:         if ( ++k <= np ) {
        !           720:           for ( i = 0; i < k; i++ )
        !           721:             win[i] = i + 1;
        !           722:           continue;
        !           723:         } else
        !           724:           break;
        !           725:       else
        !           726:         for ( i = 1; i < k; i++ )
        !           727:           win[i] = win[0] + i;
        !           728:     } else {
        !           729:       if ( ncombi(1,np,k,win) == 0 ) {
        !           730:         if ( k == np ) break;
        !           731:         else
        !           732:           for ( i = 0, ++k; i < k; i++ )
        !           733:             win[i] = i + 1;
        !           734:       }
        !           735:     }
        !           736:   }
        !           737:   reorderp(vl,nvl,f,&t);
        !           738:   /* y -> y-evy */
        !           739:   substp(vl,t,vy,yme,tl++);
        !           740:   *tl = 0;
        !           741:   for ( dc0 = 0, i = 0; l[i]; i++ ) {
        !           742:     NEXTDC(dc0,dc); DEG(dc) = ONE; COEF(dc) = l[i];
        !           743:   }
        !           744:   NEXT(dc) = 0; *dcp = dc0;
        !           745: }
        !           746:
        !           747: void next_evaluation_point(int *e,int n)
        !           748: {
        !           749:   int i,t,j;
        !           750:
        !           751:   for ( i = n-1; i >= 0; i-- )
        !           752:     if ( e[i] ) break;
        !           753:   if ( i < 0 ) e[n-1] = 1;
        !           754:   else if ( i == 0 ) {
        !           755:     t = e[0]; e[0] = 0; e[n-1] = t+1;
        !           756:   } else {
        !           757:     e[i-1]++; t = e[i];
        !           758:     for ( j = i; j < n-1; j++ )
        !           759:       e[j] = 0;
        !           760:     e[n-1] = t-1;
        !           761:   }
        !           762: }
        !           763:
        !           764: /*
        !           765:  * dc : f1^E1*...*fk^Ek
        !           766:  * find e1,...,ek s.t. fi(mev)^ei | c
        !           767:  * and return f1^e1*...*fk^ek
        !           768:  * vl = (vx,vy,rvl)
        !           769:  */
        !           770:
        !           771: void estimatelc_sf(VL vl,VL rvl,P c,DCP dc,int *mev,P *lcp)
        !           772: {
        !           773:   DCP dct;
        !           774:   P r,c1,c2,t,s,f;
        !           775:   int i,d;
        !           776:   Z q;
        !           777:
        !           778:   for ( dct = dc, r = (P)ONE; dct; dct = NEXT(dct) ) {
        !           779:     if ( NUM(COEF(dct)) )
        !           780:       continue;
        !           781:     /* constant part */
        !           782:     substvp_sf(vl,rvl,COEF(dct),mev,&f);
        !           783:     d = QTOS(DEG(dct));
        !           784:     for ( i = 0, c1 = c; i < d; i++ )
        !           785:       if ( !divtp(vl,c1,f,&c2) )
        !           786:         break;
        !           787:       else
        !           788:         c1 = c2;
        !           789:     if ( i ) {
        !           790:       STOQ(i,q);
        !           791:       pwrp(vl,COEF(dct),q,&s); mulp(vl,r,s,&t); r = t;
        !           792:     }
        !           793:   }
        !           794:   *lcp = r;
        !           795: }
        !           796:
        !           797: void substvp_sf(VL vl,VL rvl,P f,int *mev,P *r)
        !           798: {
        !           799:   int i;
        !           800:   VL tvl;
        !           801:   P g,t;
        !           802:   GFS ev;
        !           803:
        !           804:   for ( g = f, i = 0, tvl = rvl; tvl; tvl = NEXT(tvl), i++ ) {
        !           805:     if ( !mev )
        !           806:       ev = 0;
        !           807:     else
        !           808:       indextogfs(mev[i],&ev);
        !           809:     substp(vl,g,tvl->v,(P)ev,&t); g = t;
        !           810:   }
        !           811:   *r = g;
        !           812: }
        !           813:
        !           814: /*
        !           815:  * f <- f(X+sgn*mev)
        !           816:  */
        !           817:
        !           818: void shift_sf(VL vl, VL rvl, P f, int *mev, int sgn, P *r)
        !           819: {
        !           820:   VL tvl;
        !           821:   int i;
        !           822:   P x,g,t,s;
        !           823:   GFS ev;
        !           824:
        !           825:   for ( g = f, tvl = rvl, i = 0; tvl; tvl = NEXT(tvl), i++ ) {
        !           826:     if ( !mev[i] )
        !           827:       continue;
        !           828:     indextogfs(mev[i],&ev);
        !           829:     MKV(tvl->v,x);
        !           830:     if ( sgn > 0 )
        !           831:       addp(vl,x,(P)ev,&t);
        !           832:     else
        !           833:       subp(vl,x,(P)ev,&t);
        !           834:     substp(vl,g,tvl->v,t,&s); g = s;
        !           835:   }
        !           836:   *r = g;
        !           837: }
        !           838:
        !           839: /*
        !           840:  * pp(f(0)) = u0*v0
        !           841:  */
        !           842:
        !           843: void mfctrsf_hensel(VL vl,VL rvl,P f,P pp0,P u0,P v0,P lcu,P lcv,int *mev,P *up)
        !           844: {
        !           845:   VL tvl,onevl;
        !           846:   P t,s,w,u,v,ff,si,wu,wv,fj,cont;
        !           847:   UM ydy;
        !           848:   V vx,vy;
        !           849:   int dy,n,i,dbd,nv,j;
        !           850:   int *md;
        !           851:   P *uh,*vh;
        !           852:   P x,du0,dv0,m,q,r,fin;
        !           853:   P *cu,*cv;
        !           854:   GFSN inv;
        !           855:
        !           856:   /* check the validity of lc's and adjust coeffs */
        !           857:   /* f                -> lcu*lcv*x^(m+l)+... */
        !           858:   mulp(vl,lcu,lcv,&t);
        !           859:   if ( !divtp(vl,t,LC(f),&m) ) {
        !           860:     *up = 0; return;
        !           861:   }
        !           862:   mulp(vl,m,f,&t); f = t;
        !           863:   /* u0 = am x^m+ ... -> lcu*x^m + a(m-1)*(lcu(mev)/am)*x^(m-1)+... */
        !           864:   /* v0 = bm x^l+ ... -> lcv*x^l + b(l-1)*(lcv(mev)/bl)*x^(l-1)+... */
        !           865:   adjust_coef_sf(vl,rvl,lcu,u0,mev,&u);
        !           866:   adjust_coef_sf(vl,rvl,lcv,v0,mev,&v);
        !           867:
        !           868:   /* f <- f(X+mev), u <- u(X+mev), v <- v(X+mev) */
        !           869:   fin = f;
        !           870:   shift_sf(vl,rvl,f,mev,1,&s); f = s;
        !           871:   shift_sf(vl,rvl,u,mev,1,&s); u = s;
        !           872:   shift_sf(vl,rvl,v,mev,1,&s); v = s;
        !           873:
        !           874:   vx = vl->v; vy = NEXT(vl)->v;
        !           875:   n = getdeg(vx,f);
        !           876:   dy = getdeg(vy,f)+1;
        !           877:   MKV(vx,x);
        !           878:   cu = (P *)ALLOCA((n+1)*sizeof(P));
        !           879:   cv = (P *)ALLOCA((n+1)*sizeof(P));
        !           880:
        !           881:   /* ydy = y^dy */
        !           882:   ydy = C_UMALLOC(dy); DEG(ydy) = dy; COEF(ydy)[dy] = _onesf();
        !           883:   setmod_gfsn(ydy);
        !           884:
        !           885:   /* (R[y]/(y^dy))[x,X] */
        !           886:   poly_to_gfsn_poly(vl,f,vy,&ff);
        !           887:   poly_to_gfsn_poly(vl,u,vy,&t); u = t;
        !           888:   poly_to_gfsn_poly(vl,v,vy,&t); v = t;
        !           889:   substvp_sf(vl,rvl,u,0,&u0);
        !           890:   substvp_sf(vl,rvl,v,0,&v0);
        !           891:
        !           892:   /* compute a(x,y), b(x,y) s.t. a*u0+b*v0 = 1 mod y^dy */
        !           893:   extended_gcd_modyk(u0,v0,vx,vy,dy,&cu[0],&cv[0]);
        !           894:
        !           895:   /* dv0 = LC(v0)^(-1)*v0 mod y^dy */
        !           896:   invgfsn((GFSN)LC(v0),&inv); mulp(vl,v0,(P)inv,&dv0);
        !           897:
        !           898:   /* cu[i]*u0+cv[i]*v0 = x^i mod y^dy */
        !           899:   /* (x*cu[i])*u0+(x*cv[i])*v0 = x^(i+1) */
        !           900:   /* x*cu[i] = q*dv0+r => cu[i+1] = r */
        !           901:   /* cv[i+1]*v0 = x*cv[i]*v0+q*u0*dv0 = (x*cv[i]+q*u0*inv)*v0 */
        !           902:   for ( i = 1; i <= n; i++ ) {
        !           903:     mulp(vl,x,cu[i-1],&m); divsrp(vl,m,dv0,&q,&cu[i]);
        !           904:     mulp(vl,x,cv[i-1],&m); mulp(vl,q,(P)inv,&t);
        !           905:     mulp(vl,t,u0,&s);
        !           906:     addp(vl,m,s,&cv[i]);
        !           907:   }
        !           908:
        !           909: #if 0
        !           910:   /* XXX : check */
        !           911:   for ( i = 0; i <= n; i++ ) {
        !           912:     mulp(vl,cu[i],u0,&m); mulp(vl,cv[i],v0,&s);
        !           913:     addp(vl,m,s,&w);
        !           914:     printexpr(vl,w);
        !           915:     fprintf(asir_out,"\n");
        !           916:   }
        !           917: #endif
        !           918:
        !           919:   dbd = dbound(vx,f)+1;
        !           920:
        !           921:   /* extract homogeneous parts */
        !           922:   W_CALLOC(dbd,P,uh); W_CALLOC(dbd,P,vh);
        !           923:   for ( i = 0; i <= dbd; i++ ) {
        !           924:     exthpc(vl,vx,u,i,&uh[i]); exthpc(vl,vx,v,i,&vh[i]);
        !           925:   }
        !           926:
        !           927:   /* register degrees in each variables */
        !           928:   for ( nv = 0, tvl = rvl; tvl; tvl = NEXT(tvl), nv++ );
        !           929:   md = (int *)ALLOCA(nv*sizeof(int));
        !           930:   for ( i = 0, tvl = rvl; i < nv; tvl = NEXT(tvl), i++ )
        !           931:     md[i] = getdeg(tvl->v,f);
        !           932:
        !           933:   /* XXX for removing content of factor wrt vx */
        !           934:   NEWVL(onevl); onevl->v = vx; NEXT(onevl) = 0;
        !           935:
        !           936:   for ( j = 1; j <= dbd; j++ ) {
        !           937:     for ( i = 0, tvl = rvl; i < nv; tvl = NEXT(tvl), i++ )
        !           938:       if ( getdeg(tvl->v,u)+getdeg(tvl->v,v) > md[i] ) {
        !           939:         *up = 0;
        !           940:         return;
        !           941:       }
        !           942:     for ( i = 0, t = 0; i <= j; i++ ) {
        !           943:       mulp(vl,uh[i],vh[j-i],&s); addp(vl,s,t,&w); t = w;
        !           944:     }
        !           945:
        !           946:     /* s = degree j part of (f-uv) */
        !           947:     exthpc(vl,vx,ff,j,&fj); subp(vl,fj,t,&s);
        !           948:     for ( i = 0, wu = 0, wv = 0; i <= n; i++ ) {
        !           949:       if ( !s )
        !           950:         si = 0;
        !           951:       else if ( VR(s) == vx )
        !           952:         coefp(s,i,&si);
        !           953:       else if ( i == 0 )
        !           954:         si = s;
        !           955:       else
        !           956:         si = 0;
        !           957:       if ( si ) {
        !           958:         mulp(vl,si,cv[i],&m); addp(vl,wu,m,&t); wu = t;
        !           959:         mulp(vl,si,cu[i],&m); addp(vl,wv,m,&t); wv = t;
        !           960:       }
        !           961:     }
        !           962:     if ( !wu ) {
        !           963:       gfsn_poly_to_poly(vl,u,vy,&t);
        !           964:       shift_sf(vl,rvl,t,mev,-1,&s);
        !           965:       if ( divtp(vl,fin,s,&q) ) {
        !           966:         cont_pp_mv_sf(vl,onevl,s,&cont,up);
        !           967:         return;
        !           968:       }
        !           969:     }
        !           970:     if ( !wv ) {
        !           971:       gfsn_poly_to_poly(vl,v,vy,&t);
        !           972:       shift_sf(vl,rvl,t,mev,-1,&s);
        !           973:       if ( divtp(vl,fin,s,&q) ) {
        !           974:         cont_pp_mv_sf(vl,onevl,q,&cont,up);
        !           975:         return;
        !           976:       }
        !           977:     }
        !           978:     addp(vl,u,wu,&t); u = t;
        !           979:     addp(vl,uh[j],wu,&t); uh[j] = t;
        !           980:     addp(vl,v,wv,&t); v = t;
        !           981:     addp(vl,vh[j],wv,&t); vh[j] = t;
        !           982:   }
        !           983:   gfsn_poly_to_poly(vl,u,vy,&t);
        !           984:   shift_sf(vl,rvl,t,mev,-1,&s);
        !           985:   if ( divtp(vl,fin,s,&q) )
        !           986:     cont_pp_mv_sf(vl,onevl,s,&cont,up);
        !           987:   else
        !           988:     *up = 0;
        !           989: }
        !           990:
        !           991: void adjust_coef_sf(VL vl,VL rvl,P lcu,P u0,int *mev,P *r)
        !           992: {
        !           993:   P lcu0,cu;
        !           994:   DCP dc0,dcu,dc;
        !           995:
        !           996:   substvp_sf(vl,rvl,lcu,mev,&lcu0);
        !           997:   divsp(vl,lcu0,LC(u0),&cu);
        !           998:   for ( dc0 = 0, dcu = DC(u0); dcu; dcu = NEXT(dcu) ) {
        !           999:     if ( !dc0 ) {
        !          1000:       NEXTDC(dc0,dc);
        !          1001:       COEF(dc) = lcu;
        !          1002:     } else {
        !          1003:       NEXTDC(dc0,dc);
        !          1004:       mulp(vl,cu,COEF(dcu),&COEF(dc));
        !          1005:     }
        !          1006:     DEG(dc) = DEG(dcu);
        !          1007:   }
        !          1008:   NEXT(dc) = 0;
        !          1009:   MKP(VR(u0),dc0,*r);
        !          1010: }
        !          1011:
        !          1012: void extended_gcd_modyk(P u0,P v0,V x,V y,int dy,P *cu,P *cv)
        !          1013: {
        !          1014:   BM g,h,a,b;
        !          1015:
        !          1016:   gfsn_univariate_to_sfbm(u0,dy,&g);
        !          1017:   gfsn_univariate_to_sfbm(v0,dy,&h);
        !          1018:   sfexgcd_by_hensel(g,h,dy,&a,&b);
        !          1019:   sfbm_to_gfsn_univariate(a,x,y,cu);
        !          1020:   sfbm_to_gfsn_univariate(b,x,y,cv);
        !          1021: }
        !          1022:
        !          1023: /* (F[y])[x] -> F[x][y] */
        !          1024:
        !          1025: void gfsn_univariate_to_sfbm(P f,int dy,BM *r)
        !          1026: {
        !          1027:   int dx,d,i;
        !          1028:   BM b;
        !          1029:   UM cy;
        !          1030:   DCP dc;
        !          1031:
        !          1032:   dx = getdeg(VR(f),f);
        !          1033:   b = BMALLOC(dx,dy);
        !          1034:   DEG(b) = dy;
        !          1035:   for ( dc = DC(f); dc; dc = NEXT(dc) ) {
        !          1036:     /* d : degree in x, cy : poly in y */
        !          1037:     d = QTOS(DEG(dc));
        !          1038:     cy = BDY((GFSN)COEF(dc));
        !          1039:     for ( i = DEG(cy); i >= 0; i-- )
        !          1040:       COEF(COEF(b)[i])[d] = COEF(cy)[i];
        !          1041:   }
        !          1042:   for ( i = 0; i <= dy; i++ )
        !          1043:     degum(COEF(b)[i],dx);
        !          1044:   *r = b;
        !          1045: }
        !          1046:
        !          1047: void sfbm_to_gfsn_univariate(BM f,V x,V y,P *r)
        !          1048: {
        !          1049:   P g;
        !          1050:   VL vl;
        !          1051:
        !          1052:   sfbmtop(f,x,y,&g);
        !          1053:   NEWVL(vl); vl->v = x;
        !          1054:   NEWVL(NEXT(vl)); NEXT(vl)->v = y;
        !          1055:   NEXT(NEXT(vl)) = 0;
        !          1056:   poly_to_gfsn_poly(vl,g,y,r);
        !          1057: }
        !          1058:
        !          1059: void poly_to_gfsn_poly(VL vl,P f,V v,P *r)
        !          1060: {
        !          1061:   VL tvl,nvl0,nvl;
        !          1062:   P g;
        !          1063:
        !          1064:   /* (x,y,...,v,...) -> (x,y,...,v) */
        !          1065:   for ( nvl0 = 0, tvl = vl; tvl; tvl = NEXT(tvl) ) {
        !          1066:     if ( tvl->v != v ) {
        !          1067:       NEXTVL(nvl0,nvl);
        !          1068:       nvl->v = tvl->v;
        !          1069:     }
        !          1070:   }
        !          1071:   NEXTVL(nvl0,nvl);
        !          1072:   nvl->v = v;
        !          1073:   NEXT(nvl) = 0;
        !          1074:   reorderp(nvl0,vl,f,&g);
        !          1075:   poly_to_gfsn_poly_main(g,v,r);
        !          1076: }
        !          1077:
        !          1078: void poly_to_gfsn_poly_main(P f,V v,P *r)
        !          1079: {
        !          1080:   int d;
        !          1081:   UM u;
        !          1082:   GFSN g;
        !          1083:   DCP dc,dct,dc0;
        !          1084:
        !          1085:   if ( !f )
        !          1086:     *r = f;
        !          1087:   else if ( NUM(f) || VR(f) == v ) {
        !          1088:     d = getdeg(v,f);
        !          1089:     u = UMALLOC(d);
        !          1090:     ptosfum(f,u);
        !          1091:     MKGFSN(u,g);
        !          1092:     *r = (P)g;
        !          1093:   } else {
        !          1094:     for ( dc0 = 0, dct = DC(f); dct; dct = NEXT(dct) ) {
        !          1095:       NEXTDC(dc0,dc);
        !          1096:       DEG(dc) = DEG(dct);
        !          1097:       poly_to_gfsn_poly_main(COEF(dct),v,&COEF(dc));
        !          1098:     }
        !          1099:     NEXT(dc) = 0;
        !          1100:     MKP(VR(f),dc0,*r);
        !          1101:   }
        !          1102: }
        !          1103:
        !          1104: void gfsn_poly_to_poly(VL vl,P f,V v,P *r)
        !          1105: {
        !          1106:   VL tvl,nvl0,nvl;
        !          1107:   P g;
        !          1108:
        !          1109:   gfsn_poly_to_poly_main(f,v,&g);
        !          1110:   /* (x,y,...,v,...) -> (x,y,...,v) */
        !          1111:   for ( nvl0 = 0, tvl = vl; tvl; tvl = NEXT(tvl) ) {
        !          1112:     if ( tvl->v != v ) {
        !          1113:       NEXTVL(nvl0,nvl);
        !          1114:       nvl->v = tvl->v;
        !          1115:     }
        !          1116:   }
        !          1117:   NEXTVL(nvl0,nvl);
        !          1118:   nvl->v = v;
        !          1119:   NEXT(nvl) = 0;
        !          1120:   reorderp(vl,nvl0,g,r);
        !          1121: }
        !          1122:
        !          1123: void gfsn_poly_to_poly_main(P f,V v,P *r)
        !          1124: {
        !          1125:   DCP dc,dc0,dct;
        !          1126:
        !          1127:   if ( !f )
        !          1128:     *r = f;
        !          1129:   else if ( NUM(f) ) {
        !          1130:     if ( NID((Num)f) == N_GFSN )
        !          1131:       sfumtop(v,BDY((GFSN)f),r);
        !          1132:     else
        !          1133:       *r = f;
        !          1134:   } else {
        !          1135:     for ( dc0 = 0, dct = DC(f); dct; dct = NEXT(dct) ) {
        !          1136:       NEXTDC(dc0,dc);
        !          1137:       DEG(dc) = DEG(dct);
        !          1138:       gfsn_poly_to_poly_main(COEF(dct),v,&COEF(dc));
        !          1139:     }
        !          1140:     NEXT(dc) = 0;
        !          1141:     MKP(VR(f),dc0,*r);
        !          1142:   }
        !          1143: }
        !          1144:
        !          1145: void printsfum(UM f)
        !          1146: {
        !          1147:   int i;
        !          1148:
        !          1149:   for ( i = DEG(f); i >= 0; i-- ) {
        !          1150:     printf("+(");
        !          1151:     printf("%d",IFTOF(COEF(f)[i]));
        !          1152:     printf(")*y^%d",i);
        !          1153:   }
        !          1154: }
        !          1155:
        !          1156: void printsfbm(BM f)
        !          1157: {
        !          1158:   int i;
        !          1159:
        !          1160:   for ( i = DEG(f); i >= 0; i-- ) {
        !          1161:     printf("+(");
        !          1162:     printsfum(COEF(f)[i]);
        !          1163:     printf(")*y^%d",i);
        !          1164:   }
        !          1165: }
        !          1166:

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