===================================================================
RCS file: /home/cvs/OpenXM_contrib2/asir2000/engine/Hgfs.c,v
retrieving revision 1.26
retrieving revision 1.28
diff -u -p -r1.26 -r1.28
--- OpenXM_contrib2/asir2000/engine/Hgfs.c	2002/10/25 02:43:40	1.26
+++ OpenXM_contrib2/asir2000/engine/Hgfs.c	2002/11/22 07:32:10	1.28
@@ -1,4 +1,4 @@
-/* $OpenXM: OpenXM_contrib2/asir2000/engine/Hgfs.c,v 1.25 2002/10/23 07:54:58 noro Exp $ */
+/* $OpenXM: OpenXM_contrib2/asir2000/engine/Hgfs.c,v 1.27 2002/11/01 05:43:35 noro Exp $ */
 
 #include "ca.h"
 #include "inline.h"
@@ -506,21 +506,21 @@ void canzassf(UM f,int d,UM *r)
 
 /* Hensel related functions */
 
-int sfberle(VL,P,int,GFS *,DCP *);
+int sfberle(V,V,P,int,GFS *,DCP *);
 void sfgcdgen(P,ML,ML *);
 void sfhenmain2(BM,UM,UM,int,BM *);
 void ptosfbm(int,P,BM);
+void sfhensel(int count,P f,V x,V y,int degbound,GFS *evp,P *sfp,ML *listp);
 
 /* f = f(x,y) */
 
-void sfhensel(int count,P f,V x,int degbound,GFS *evp,P *sfp,ML *listp)
+void sfhensel(int count,P f,V x,V y,int degbound,GFS *evp,P *sfp,ML *listp)
 {
 	int i;
 	int fn;
 	ML rlist;
 	BM fl;
 	VL vl,nvl;
-	V y;
 	int dx,dy,bound;
 	GFS ev;
 	P f1,t,c,sf;
@@ -534,14 +534,15 @@ void sfhensel(int count,P f,V x,int degbound,GFS *evp,
 		reordvar(vl,x,&nvl); reorderp(nvl,vl,f,&f1);
 		vl = nvl; f = f1;
 	}
-	y = vl->next->v;
+	if ( vl->next )
+		y = vl->next->v;
 	dx = getdeg(x,f);
 	dy = getdeg(y,f);
 	if ( dx == 1 ) {
 		*listp = rlist = MLALLOC(1); rlist->n = 1; rlist->c[0] = 0;
 		return;
 	}
-	fn = sfberle(vl,f,count,&ev,&dc);
+	fn = sfberle(x,y,f,count,&ev,&dc);
 	if ( fn <= 1 ) {
 		/* fn == 0 => short of evaluation points */
 		*listp = rlist = MLALLOC(1); rlist->n = fn; rlist->c[0] = 0;
@@ -640,20 +641,20 @@ void sfhensel(int count,P f,V x,int degbound,GFS *evp,
 
 /* main variable of f = x */
 
-int sfberle(VL vl,P f,int count,GFS *ev,DCP *dcp)
+int sfberle(V x,V y,P f,int count,GFS *ev,DCP *dcp)
 {
 	UM wf,wf1,wf2,wfs,gcd;
 	int fn,n;
 	GFS m,fm;
 	DCP dc,dct,dc0;
-	VL nvl;
-	V x,y;
+	VL vl;
 	P lc,lc0,f0;
 	Obj obj;
 	int j,q,index,i;
 
-	clctv(vl,f,&nvl); vl = nvl;
-	x = vl->v; y = vl->next->v;
+	NEWVL(vl); vl->v = x;
+	NEWVL(NEXT(vl)); NEXT(vl)->v = y;
+	NEXT(NEXT(vl)) =0;
 	simp_ff((Obj)f,&obj); f = (P)obj;
 	n = QTOS(DEG(DC(f)));
 	wf = W_UMALLOC(n); wf1 = W_UMALLOC(n); wf2 = W_UMALLOC(n);
@@ -821,6 +822,93 @@ void sfhenmain2(BM f,UM g0,UM h0,int dy,BM *gp)
 		cpyum(COEF(hk)[i],COEF(f)[i]);
 }
 
+/* a0*g+b0*h = 1 mod y -> a*g+b*h = 1 mod y^(dy+1) */
+
+void sfexgcd_by_hensel(BM g,BM h,int dy,BM *ap,BM *bp)
+{
+	int i,k;
+	int dx;
+	UM wt,wa,wb,q,w1,w2,ws;
+	UM wc,wd,we,wz,wa1,wb1;
+	BM wz0,wz1;
+	int dg,dh;
+	BM a,b,c;
+
+	dg = degbm(g);
+	dh = degbm(h);
+	dx = dg+dh;
+
+	a = BMALLOC(dh,dy);
+	b = BMALLOC(dg,dy);
+	/* c holds a*g+b*h-1 */
+	c = BMALLOC(dg+dh,dy);
+
+	W_BMALLOC(dx,dy,wz0); W_BMALLOC(dx,dy,wz1);
+
+	wt = W_UMALLOC(dx); ws = W_UMALLOC(dx); q = W_UMALLOC(2*dx);
+	wa1 = W_UMALLOC(2*dx); wb1 = W_UMALLOC(2*dx);
+	wc = W_UMALLOC(2*dx); wd = W_UMALLOC(2*dx);
+	we = W_UMALLOC(2*dx); wz = W_UMALLOC(2*dx);
+
+	/* compute wa,wb s.t. wa*g0+wb*h0 = 1 mod y */
+	w1 = W_UMALLOC(dg); cpyum(COEF(g)[0],w1);
+	w2 = W_UMALLOC(dh); cpyum(COEF(h)[0],w2);
+	wa = W_UMALLOC(2*dx); wb = W_UMALLOC(2*dx);  /* XXX */
+	eucsfum(w1,w2,wa,wb);
+	cpyum(wa,COEF(a)[0]); cpyum(wb,COEF(b)[0]);
+	
+	/* initialize c to a*g+b*h-1 */
+	mulsfbm(a,g,c); mulsfbm(b,h,wz0); addtosfbm(wz0,c);
+	COEF(COEF(c)[0])[0] = 0;
+	
+	fprintf(stderr,"dy=%d\n",dy);
+	for ( k = 1; k <= dy; k++ ) {
+		fprintf(stderr,".");
+
+		/* at this point, a*g+b*h = 1 mod y^k, c = a*g+b*h-1 */
+
+		/* wt = -((a*g+b*h-1)/y^k) */
+		cpyum(COEF(c)[k],wt);
+		for ( i = DEG(wt); i >= 0; i-- )
+			COEF(wt)[i] = _chsgnsf(COEF(wt)[i]);
+		
+		/* compute wa1,wb1 s.t. wa1*g0+wb1*h0 = wt */
+		mulsfum(wa,wt,wa1); DEG(wa1) = divsfum(wa1,COEF(h)[0],q);
+		mulsfum(wa1,COEF(g)[0],wc); subsfum(wt,wc,wd); 
+		DEG(wd) = divsfum(wd,COEF(h)[0],wb1);
+
+		/* c += ((wa1*g+wb1*h)*y^k mod y^(dy+1) */
+		/* wz0 = wa1*y^k */
+		clearbm(dx,wz0);
+		cpyum(wa1,COEF(wz0)[k]);
+
+		/* wz1 = wz0*g mod y^(dy+1) */
+		clearbm(dx,wz1);
+		mulsfbm(g,wz0,wz1);
+		/* c += wz1 */
+		addtosfbm(wz1,c);
+
+		/* wz0 = wb1*y^k */
+		clearbm(dx,wz0);
+		cpyum(wb1,COEF(wz0)[k]);
+
+		/* wz1 = wz0*h mod y^(dy+1) */
+		clearbm(dx,wz1);
+		mulsfbm(h,wz0,wz1);
+		/* c += wz1 */
+		addtosfbm(wz1,c);
+
+		/* a += wa1*y^k, b += wb1*y^k */
+		cpyum(wa1,COEF(a)[k]);
+		cpyum(wb1,COEF(b)[k]);
+	}
+	fprintf(stderr,"\n");
+	DEG(a) = dy;
+	DEG(b) = dy;
+	*ap = a;
+	*bp = b;
+}
+
 /* fl->c[i] = coef_y(f,i) */
 
 void ptosfbm(int dy,P f,BM fl)
@@ -990,7 +1078,7 @@ void sfbfctr(P f,V x,V y,int degbound,DCP *dcp)
 	int dx,dy;
 
 	/* sf(x) = f(x+ev) = list->c[0]*list->c[1]*... */
-	sfhensel(5,f,x,degbound,&ev,&sf,&list);
+	sfhensel(5,f,x,y,degbound,&ev,&sf,&list);
 	if ( list->n == 0 )
 		error("sfbfctr : short of evaluation points");
 	else if ( list->n == 1 ) {
@@ -1024,7 +1112,7 @@ void sfbfctr_shift(P f,V x,V y,int degbound,GFS *evp,P
 	int dx,dy;
 
 	/* sf(x) = f(x+ev) = list->c[0]*list->c[1]*... */
-	sfhensel(5,f,x,degbound,&ev,&sf,&list);
+	sfhensel(5,f,x,y,degbound,&ev,&sf,&list);
 	if ( list->n == 0 )
 		error("sfbfctr_shift : short of evaluation points");
 	else if ( list->n == 1 ) {