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Annotation of OpenXM/src/asir-contrib/packages/src/taka_runge_kutta.rr, Revision 1.18

1.18    ! takayama    1: /* $OpenXM: OpenXM/src/asir-contrib/packages/src/taka_runge_kutta.rr,v 1.17 2010/04/18 01:08:37 takayama Exp $ */
1.1       takayama    2: /* From misc/200205/runge-kutta.rr */
                      3:
                      4: /* They have not yet been registered in names.rr */
                      5:
                      6: #define DEVAL(a)  eval(a)
                      7: Taka_Runge_kutta_adapted0 = 0$
                      8: Taka_Runge_kutta_epsilon = 0.1$
                      9: Taka_Runge_kutta_H_Upper_Bound = 0.2$
1.3       takayama   10: Taka_Runge_kutta_Make_Larger = 1$ /* Default 1 */
1.1       takayama   11:
                     12: Taka_Runge_kutta_graphic0 = 0$  /* load("glib"); */
                     13: Taka_Runge_kutta_yrange = 10$
                     14:
                     15: Taka_Runge_kutta_save_data = 1$
1.15      takayama   16: Taka_Runge_kutta_debug = 0$
1.1       takayama   17:
                     18: def taka_runge_kutta_2(F,X,Y,X0,Y0,H,X1) {
                     19:   extern Taka_Runge_kutta_graphic0, Taka_Runge_kutta_yrange, Taka_Runge_kutta_save_data;
                     20:   Alpha =0.5;
                     21:   Beta = 0.5;
                     22:   P = 1; Q = 1;
                     23:
                     24:   Ans = [];
                     25:   if (Taka_Runge_kutta_graphic0) {
                     26:      glib_open();
                     27:      glib_window(X0,Y0[0]-Taka_Runge_kutta_yrange,X1,Y0[0]+Taka_Runge_kutta_yrange);
                     28:   }
                     29:
                     30:   if (type(F) == 5) {
                     31:     N = size(F)[0];
                     32:   }else{
                     33:     N = length(F);
                     34:   }
                     35:   if (type(Y0) != 5) {
                     36:     Y0 = newvect(N,Y0);
                     37:   }
                     38:   Yk = Y0;
                     39:   K1 = newvect(N);
                     40:   K2 = newvect(N);
                     41:   Yk1 = newvect(N);
                     42:   Xk = X0;
                     43:
                     44:   while (Xk < X1) {
                     45:     taka_runge_kutta_replace(K1,F,Y,N,X,Xk,Yk);
                     46:     taka_runge_kutta_replace(K2,F,Y,N,X,Xk+P*H,Yk+Q*H*K1);
                     47:     Yk1 = Yk+H*Alpha*K1+H*Beta*K2;
                     48:     if (Taka_Runge_kutta_save_data) {
                     49:       Ans = cons(cons(Xk,vtol(Yk)),Ans);
                     50:     }
                     51:     print([Xk,Yk[0]]);
                     52:     if (Taka_Runge_kutta_graphic0) glib_line(Xk,Yk[0],Xk+H,Yk1[0]);
                     53:     Xk += H;
                     54:     Yk = Yk1;
                     55:   }
                     56:   return Ans;
                     57: }
                     58:
                     59: def taka_runge_kutta_2_test() {
                     60:    /* Equation of oscilations */
                     61:    F = newvect(2,[y2,-y1]);
                     62:    Y = [y1,y2];
                     63:    taka_runge_kutta_2(F,x,Y,0,[1,0],0.1,15);
                     64: }
                     65:
                     66: def taka_runge_kutta_replace(V,F,Y,N,X,Xk,Rule_vector) {
                     67:   for (I=0; I<N; I++) {
                     68:     V[I] = subst(F[I],X,Xk);
                     69:     for (J=0; J<N; J++) {
                     70:       V[I] = subst(V[I],Y[J],Rule_vector[J]);
                     71:     }
1.9       takayama   72:     V[I] = eval(V[I]*exp(0));
1.1       takayama   73:   }
                     74: }
                     75:
                     76: def taka_runge_kutta_abs(V) {
                     77:   if (type(V) != 5 && type(V) != 4) { /* not a vector */
                     78:     if (ntype(V) == 4) { /* complex number */
                     79:        return V*conj(V);
                     80:     }else{
                     81:       return(V*V);
                     82:     }
                     83:   }
                     84:   if (type(V) == 5) N = size(V)[0];
                     85:   if (type(V) == 4) N = length(V);
                     86:   S = 0;
                     87:   for (I=0; I<N; I++) {
                     88:     if (ntype(V[I]) == 4) /* complex number */
                     89:       S += V[I]*conj(V[I]);
                     90:     else
                     91:       S += V[I]*V[I];
                     92:   }
                     93:   return S;
                     94: }
                     95:
                     96: def taka_runge_kutta_4(F,X,Y,X0,Y0,H,X1) {
                     97: /* N : rank of the ODE. */
                     98:   extern Taka_Runge_kutta_adapted0, Taka_Runge_kutta_epsilon,
                     99:          Taka_Runge_kutta_graphic0, Taka_Runge_kutta_yrange,
1.12      takayama  100:          Taka_Runge_kutta_save_data, Taka_Runge_kutta_debug;
1.1       takayama  101:
1.10      takayama  102:   OneStep = getopt(onestep);
                    103:   if (type(OneStep) <= 0) OneStep = 0; else OneStep = 1;
                    104:   if (OneStep) X1=X0+2*H;
1.14      takayama  105:   if ((H<0) && (X1-X0)>0) error("taka_runge_kutta_4, X1-X0 should be <0");
                    106:   if ((H>0) && (X1-X0)<0) error("taka_runge_kutta_4, X1-X0 should be >0");
1.1       takayama  107:   Ans = [];
                    108:   if (Taka_Runge_kutta_graphic0) {
                    109:      glib_open();
                    110:      glib_window(X0,Y0[0]-Taka_Runge_kutta_yrange,X1,Y0[0]+Taka_Runge_kutta_yrange);
                    111:   }
1.12      takayama  112:   if (X0==X1) return([cons(X0,Y0)]);
1.1       takayama  113:
                    114:   if (type(F) == 5) {
                    115:     N = size(F)[0];
                    116:   }else{
                    117:     N = length(F);
                    118:   }
                    119:   if (type(Y0) != 5) {
                    120:     Y0 = newvect(N,Y0);
                    121:   }
                    122:   Yk = Y0;
                    123:   K1 = newvect(N);
                    124:   K2 = newvect(N);
                    125:   K3 = newvect(N);
                    126:   K4 = newvect(N);
                    127:   Yk1 = newvect(N);
                    128:   Xk = X0;
                    129:
1.14      takayama  130:   while (H<0? Xk > X1: Xk < X1) {
1.1       takayama  131:     taka_runge_kutta_replace(K1,F,Y,N,X,Xk,Yk);
1.3       takayama  132:     taka_runge_kutta_replace(K2,F,Y,N,X,Xk+H*(1/2),Yk+K1*(1/2)*H);
                    133:     taka_runge_kutta_replace(K3,F,Y,N,X,Xk+H*(1/2),Yk+K2*(1/2)*H);
1.1       takayama  134:     taka_runge_kutta_replace(K4,F,Y,N,X,Xk+H,Yk+K3*H);
                    135:     Yk1 = Yk+H*(K1/6+K2/3+K3/3+K4/6);
1.12      takayama  136:     if (Taka_Runge_kutta_debug) print([Xk,Yk[0]]);
1.1       takayama  137:     if (Taka_Runge_kutta_save_data) {
                    138:       Ans = cons(cons(Xk,vtol(Yk)),Ans);
                    139:     }
1.10      takayama  140:     if (OneStep) {
1.12      takayama  141:        return([cons(Xk+H,vtol(Yk1)), cons(Xk,vtol(Yk))]);
1.10      takayama  142:     }
1.1       takayama  143:     if (Taka_Runge_kutta_graphic0) glib_line(Xk,Yk[0],Xk+H,Yk1[0]);
                    144:     if (Taka_Runge_kutta_adapted0 &&
                    145:         (taka_runge_kutta_abs(Yk1-Yk) > Taka_Runge_kutta_epsilon)) {
1.3       takayama  146:       H = H*(1/2);
1.1       takayama  147:     }else{
                    148:       if (Taka_Runge_kutta_adapted0) H = H*2;
                    149:       Xk += H;
                    150:       Yk = Yk1;
                    151:     }
                    152:   }
                    153:   return Ans;
                    154: }
                    155:
                    156: def taka_runge_kutta_4_adaptive(F,X,Y,X0,Y0,H,X1) {
                    157: /* N : rank of the ODE. */
                    158:   extern Taka_Runge_kutta_epsilon,
                    159:          Taka_Runge_kutta_graphic0, Taka_Runge_kutta_yrange,
                    160:          Taka_Runge_kutta_save_data,
                    161:          Taka_Runge_kutta_H_Upper_Bound,
                    162:          Taka_Runge_kutta_Make_Larger;
                    163:
1.5       takayama  164:   Opt = getopt();
1.6       takayama  165:   if (taka_runge_kutta_complex_gt(H,0)) Forward = 1; else Forward = 0;
1.5       takayama  166:   while(Opt != []) {
                    167:     if (car(Opt)[0] == "forward") {
                    168:       Forward = car(Opt)[1];
                    169:     }
                    170:     Opt = cdr(Opt);
                    171:   }
                    172:
1.1       takayama  173:   Ans = [cons(X0,Y0)];
                    174:   if (Taka_Runge_kutta_graphic0) {
                    175:      glib_open();
                    176:      glib_window(X0,Y0[0]-Taka_Runge_kutta_yrange,X1,Y0[0]+Taka_Runge_kutta_yrange);
                    177:   }
                    178:
                    179:   if (type(F) == 5) {
                    180:     N = size(F)[0];
                    181:   }else{
                    182:     N = length(F);
                    183:   }
                    184:   if (type(Y0) != 5) {
                    185:     Y0 = newvect(N,Y0);
                    186:   }
                    187:   Yk = Y0;
                    188:   K1 = newvect(N);
                    189:   K2 = newvect(N);
                    190:   K3 = newvect(N);
                    191:   K4 = newvect(N);
                    192:   Yk1 = newvect(N);
1.3       takayama  193:   Yk2 = newvect(N);
                    194:   Yk3 = newvect(N);
1.1       takayama  195:   Xk = X0;
                    196:
                    197:   while (true) {
1.5       takayama  198:     if (Forward) {
1.6       takayama  199:        /* if (Xk > X1) break; */
                    200:        if (taka_runge_kutta_complex_gt(Xk,X1)) break;
1.5       takayama  201:     } else{
1.6       takayama  202:        /* if (Xk < X1) break; */
                    203:        if (taka_runge_kutta_complex_gt(X1,Xk)) break;
1.1       takayama  204:     }
                    205:     /* Regular step */
                    206:     taka_runge_kutta_replace(K1,F,Y,N,X,Xk,Yk);
1.3       takayama  207:     taka_runge_kutta_replace(K2,F,Y,N,X,Xk+H*(1/2),Yk+K1*(1/2)*H);
                    208:     taka_runge_kutta_replace(K3,F,Y,N,X,Xk+H*(1/2),Yk+K2*(1/2)*H);
1.1       takayama  209:     taka_runge_kutta_replace(K4,F,Y,N,X,Xk+H,Yk+K3*H);
                    210:     Yk1 = Yk+H*(K1/6+K2/3+K3/3+K4/6);
                    211:     /* half step */
                    212:     H2 = H/2;
                    213:     taka_runge_kutta_replace(K1,F,Y,N,X,Xk,Yk);
1.3       takayama  214:     taka_runge_kutta_replace(K2,F,Y,N,X,Xk+H2*(1/2),Yk+K1*(1/2)*H2);
                    215:     taka_runge_kutta_replace(K3,F,Y,N,X,Xk+H2*(1/2),Yk+K2*(1/2)*H2);
                    216:     taka_runge_kutta_replace(K4,F,Y,N,X,Xk+H2,Yk+K3*H2);
1.1       takayama  217:     Yk2 = Yk+H2*(K1/6+K2/3+K3/3+K4/6);
                    218:
1.3       takayama  219:     taka_runge_kutta_replace(K1,F,Y,N,X,Xk+H2,Yk2);
                    220:     taka_runge_kutta_replace(K2,F,Y,N,X,Xk+H2+H2*(1/2),Yk2+K1*(1/2)*H2);
                    221:     taka_runge_kutta_replace(K3,F,Y,N,X,Xk+H2+H2*(1/2),Yk2+K2*(1/2)*H2);
                    222:     taka_runge_kutta_replace(K4,F,Y,N,X,Xk+H2+H2,Yk2+K3*H2);
                    223:     Yk3 = Yk2+H2*(K1/6+K2/3+K3/3+K4/6);
                    224:
                    225:     /* This is a strategy which you may change. */
1.4       takayama  226:     /* WantedPrec = Taka_Runge_kutta_epsilon*taka_runge_kutta_abs(Yk);*/
                    227:     WantedPrec = Taka_Runge_kutta_epsilon;
1.3       takayama  228:
                    229:     Delta1 = DEVAL(taka_runge_kutta_abs(Yk3-Yk1));
                    230:     if (Delta1 != 0) {
                    231:       Habs = DEVAL((WantedPrec/Delta1)^(1/5));
                    232:       Habs = (4/5)*Habs; /* 0.8 = (4/5) is the safety factor */
                    233:     }else{
                    234:       Habs = 2; /* Any large number */
                    235:     }
1.4       takayama  236:     /* print("Habs="+rtostr(Habs)); */
1.3       takayama  237:     if (Habs < 1) { /* Compute again.  */
                    238:       H = H*Habs;
1.1       takayama  239:       print("Changing to Smaller step size: "+rtostr(H));
                    240:       print([Xk,Yk[0]]);
                    241:     }else{  /* Go ahead */
                    242:       Xk += H;
                    243:       Yk = Yk1;
1.3       takayama  244:       if ((H<Taka_Runge_kutta_H_Upper_Bound) && Taka_Runge_kutta_Make_Larger) {
                    245:         H = (Habs*H > Taka_Runge_kutta_H_Upper_Bound?
1.4       takayama  246:              (H/number_abs(H))*Taka_Runge_kutta_H_Upper_Bound :
1.3       takayama  247:              Habs*H);  /* Habs*H2*2 */
1.1       takayama  248:         print("Changing to a larger step size: "+rtostr(H));
                    249:       }
                    250:       print([Xk,Yk[0]]);
                    251:       if (Taka_Runge_kutta_save_data) {
                    252:         Ans = cons(cons(Xk,vtol(Yk)),Ans);
                    253:       }
                    254:       if (Taka_Runge_kutta_graphic0) glib_line(Xk,Yk[0],Xk+H,Yk1[0]);
                    255:     }
                    256:   }
                    257:   return Ans;
                    258: }
                    259:
                    260: /* load("glib"); load("taka_plot.rr"); to execute the functions below. */
                    261: def taka_runge_kutta_4_a_test() {
                    262:    /* exponential function */
                    263:    F = newvect(1,[y1]);
                    264:    Y = [y1];
1.3       takayama  265:    T = taka_runge_kutta_4_adaptive(F,x,Y,0,[1],0.1,5);
                    266:    taka_plot_auto(T);
1.13      takayama  267:    print("Eval by eval(exp(?)) : ",0); print([T[0][0],eval(exp(T[0][0]))]);
1.3       takayama  268: }
                    269:
                    270: def taka_runge_kutta_4_a2_test() {
                    271:    /* Equation of oscilations */
                    272:    F = newvect(2,[y2,-y1]);
                    273:    Y = [y1,y2];
                    274:    T = taka_runge_kutta_4_adaptive(F,x,Y,0,[1,0],0.1,15);
1.1       takayama  275:    taka_plot_auto(T);
1.13      takayama  276:    print("Eval by eval((?)) : ",0); print([T[0][0],eval(cos(T[0][0]))]);
1.1       takayama  277: }
                    278:
                    279: def taka_runge_kutta_4_test() {
                    280:    /* Equation of oscilations */
                    281:    F = newvect(2,[y2,-y1]);
                    282:    Y = [y1,y2];
                    283:    T=taka_runge_kutta_4(F,x,Y,0,[1,0],0.1,15);
                    284:    print(T);
                    285:    taka_plot_auto(T);
                    286: }
                    287:
1.14      takayama  288: def taka_runge_kutta_4_test2() {
                    289:    /* Equation of oscilations */
                    290:    F = newvect(2,[y2,-y1]);
                    291:    Y = [y1,y2];
                    292:    T=taka_runge_kutta_4(F,x,Y,15,[1,0],-0.1,0);
                    293:    print(T);
                    294:    taka_plot_auto(T);
                    295: }
                    296:
1.15      takayama  297: def taka_runge_kutta_replace_linear(V,F,Y,N,X,Xk,Rule_vector) {
                    298:   V1=base_replace_n(F,[[X,Xk]]);
                    299:   V1=V1*Rule_vector;
                    300:   for (I=0; I<N; I++) {
                    301:     V[I] = V1[I];
                    302:   }
                    303: }
                    304:
                    305: /* Y is a dummy */
                    306: def taka_runge_kutta_4_linear(F,X,Y,X0,Y0,H,X1) {
                    307: /* N : rank of the ODE. */
                    308:   extern Taka_Runge_kutta_adapted0, Taka_Runge_kutta_epsilon,
                    309:          Taka_Runge_kutta_graphic0, Taka_Runge_kutta_yrange,
                    310:          Taka_Runge_kutta_save_data, Taka_Runge_kutta_debug;
                    311:
                    312:   OneStep = getopt(onestep);
                    313:   if (type(OneStep) <= 0) OneStep = 0; else OneStep = 1;
                    314:   if (OneStep) X1=X0+2*H;
                    315:   if ((H<0) && (X1-X0)>0) error("taka_runge_kutta_4_linear, X1-X0 should be <0");
                    316:   if ((H>0) && (X1-X0)<0) error("taka_runge_kutta_4_linear, X1-X0 should be >0");
                    317:   Ans = [];
                    318:   if (Taka_Runge_kutta_graphic0) {
                    319:      glib_open();
                    320:      glib_window(X0,Y0[0]-Taka_Runge_kutta_yrange,X1,Y0[0]+Taka_Runge_kutta_yrange);
                    321:   }
                    322:   if (X0==X1) return([cons(X0,Y0)]);
                    323:
                    324:   if (type(F) == 4) {
                    325:     F=newmat(length(F),length(F[0]),F);
                    326:   }
                    327:   N = size(F)[0];
                    328:
                    329:   if (type(Y0) != 5) {
                    330:     Y0 = newvect(N,Y0);
                    331:   }
                    332:   Yk = Y0;
                    333:   K1 = newvect(N);
                    334:   K2 = newvect(N);
                    335:   K3 = newvect(N);
                    336:   K4 = newvect(N);
                    337:   Yk1 = newvect(N);
                    338:   Xk = X0;
                    339:
                    340:   while (H<0? Xk > X1: Xk < X1) {
                    341:     taka_runge_kutta_replace_linear(K1,F,Y,N,X,Xk,Yk);
                    342:     taka_runge_kutta_replace_linear(K2,F,Y,N,X,Xk+H*(1/2),Yk+K1*(1/2)*H);
                    343:     taka_runge_kutta_replace_linear(K3,F,Y,N,X,Xk+H*(1/2),Yk+K2*(1/2)*H);
                    344:     taka_runge_kutta_replace_linear(K4,F,Y,N,X,Xk+H,Yk+K3*H);
                    345:     Yk1 = Yk+H*(K1/6+K2/3+K3/3+K4/6);
                    346:     if (Taka_Runge_kutta_debug) print([Xk,Yk[0]]);
                    347:     if (Taka_Runge_kutta_save_data) {
                    348:       Ans = cons(cons(Xk,vtol(Yk)),Ans);
                    349:     }
                    350:     if (OneStep) {
                    351:        return([cons(Xk+H,vtol(Yk1)), cons(Xk,vtol(Yk))]);
                    352:     }
                    353:     if (Taka_Runge_kutta_graphic0) glib_line(Xk,Yk[0],Xk+H,Yk1[0]);
                    354:     if (Taka_Runge_kutta_adapted0 &&
                    355:         (taka_runge_kutta_abs(Yk1-Yk) > Taka_Runge_kutta_epsilon)) {
                    356:       H = H*(1/2);
                    357:     }else{
                    358:       if (Taka_Runge_kutta_adapted0) H = H*2;
                    359:       Xk += H;
                    360:       Yk = Yk1;
                    361:     }
                    362:   }
                    363:   return Ans;
                    364: }
                    365:
                    366: def taka_runge_kutta_4_linear_test() {
                    367:    /* Airy equation y''-x y = 0
                    368:     [evalf(AiryAi(0)),evalf(subs(x=0,diff(AiryAi(x),x)))];
                    369:     Y0=[0.3550280540, -0.2588194038]
                    370:     evalf(AiryAi(-5)); --> 0.35076
                    371:    */
                    372:    F = [[0,1],[x,0]];
                    373:    Y = [y1,y2];
                    374:    Y0=[0.3550280540, -0.2588194038];
                    375:    T=taka_runge_kutta_4_linear(F,x,Y,0,Y0,-0.1,-5);
                    376:    print(T);
                    377:    taka_plot_auto(T);
                    378:    T2=taka_runge_kutta_4([y2,x*y1],x,Y,0,Y0,-0.1,-5);
                    379:    print("AiryAi(-5) --> 0.35076");
                    380:    return([T[0],T2[0]]);
                    381: }
                    382:
                    383: /*
                    384: def base_replace_n(F,R) { return base_replace(F,R); }
                    385: */
1.6       takayama  386:
                    387: /* cf. asir2000/engine/cplx.c  int cmpcplx(a,b),
                    388:        which does not compare the real part and imaginary part.
                    389:        Instead, it compares NID (number id)
                    390: */
                    391: def taka_runge_kutta_complex_gt(A,B) {
                    392:   Ar = number_real_part(A); Ai = number_imaginary_part(A);
                    393:   Br = number_real_part(B); Bi = number_imaginary_part(B);
                    394:   if (Ar > Br) return 1;
                    395:   else if (Ar < Br) return 0;
                    396:   if (Ai > Bi) return 1;
                    397:   else if (Ai < Bi) return 0;
                    398:   return 0;
                    399: }
1.1       takayama  400:
                    401: Loaded_taka_runge_kutta=1$
1.7       takayama  402:
                    403: /* cf. misc-2003/09/neval/ellip.*  */
                    404: /* runge_kutta_4 is still buggy for complex numbers */
                    405:
1.16      takayama  406: module tk_rk;
                    407: localf taka_minus;
                    408: localf taka_runge_kutta_reverse ;
                    409: localf taka_runge_kutta_4a;
                    410: localf taka_runge_kutta_4a_linear;
                    411: localf test4 ;
                    412: localf test4b ;
1.18    ! takayama  413: localf runge_kutta_4;
        !           414: localf runge_kutta_4_linear;
1.16      takayama  415: def taka_minus(Ob) {
1.17      takayama  416:   if (type(Ob) != 4) return(-Ob);
                    417:   else return map(taka_minus,Ob);
1.16      takayama  418: }
                    419: def taka_runge_kutta_reverse(A) {
                    420:   B=[];
                    421:   for (; length(A) != 0; A=cdr(A)) {
                    422:      T=car(A);
                    423:      B=cons(cons(-T[0],cdr(T)),B);
                    424:   }
                    425:   return reverse(B);
                    426: }
                    427: def taka_runge_kutta_4a(FF,X0,Y,S0,Ys,T0,H) {
                    428:   if (T0 < S0) {
                    429:     /* opposite direction */
                    430:     return taka_runge_kutta_reverse(
                    431:       taka_runge_kutta_4a(map(taka_minus,base_replace(FF,[[X0,-X0]])),X0,Y,-S0,Ys,-T0,H));
                    432:   }
                    433:   if (H >= T0-S0) {
                    434:     A=taka_runge_kutta_4(FF,X0,Y,S0,Ys,T0-S0,0 | onestep=1);
                    435:   }else{
                    436:     A=taka_runge_kutta_4(FF,X0,Y,S0,Ys,H,T0);
                    437:     T=A[0];
                    438:     if (T0-T[0] > 0) {
                    439:       B=taka_runge_kutta_4(FF,X0,Y,T[0],cdr(T),T0-T[0],0 | onestep=1);
                    440:       T=B[0];
                    441:       A=cons(T,A);
                    442:     }
                    443:  }
                    444:  return(A);
                    445: }
1.18    ! takayama  446: def runge_kutta_4(FF,X0,Y,S0,Ys,T0,H) {
        !           447:    return taka_runge_kutta_4a(FF,X0,Y,S0,Ys,T0,H);
        !           448: }
        !           449: def runge_kutta_4_linear(FF,X0,Y,S0,Ys,T0,H) {
        !           450:    return taka_runge_kutta_4a_linear(FF,X0,Y,S0,Ys,T0,H);
        !           451: }
1.16      takayama  452:
                    453: def taka_runge_kutta_4a_linear(FF,X0,Y,S0,Ys,T0,H) {
1.17      takayama  454:   if (T0 < S0) {
                    455:     /* opposite direction */
                    456:     return taka_runge_kutta_reverse(
                    457:       taka_runge_kutta_4a_linear(map(taka_minus,base_replace(FF,[[X0,-X0]])),X0,Y,-S0,Ys,-T0,H));
                    458:   }
1.16      takayama  459:   if (H >= T0-S0) {
                    460:     A=taka_runge_kutta_4_linear(FF,X0,Y,S0,Ys,T0-S0,0 | onestep=1);
                    461:   }else{
                    462:     A=taka_runge_kutta_4_linear(FF,X0,Y,S0,Ys,H,T0);
                    463:     T=A[0];
                    464:     if (T0-T[0] > 0) {
                    465:       B=taka_runge_kutta_4_linear(FF,X0,Y,T[0],cdr(T),T0-T[0],0 | onestep=1);
                    466:       T=B[0];
                    467:       A=cons(T,A);
                    468:     }
                    469:  }
                    470:  return(A);
                    471: }
                    472:
                    473: /* equation of oscilation */
                    474: def test4() {
1.18    ! takayama  475:   A=runge_kutta_4([y1,-y0],x,[y0,y1],0,[1,0],3.14*2,0.1);
1.16      takayama  476:   taka_plot_auto(A);
                    477:   return(A);
                    478: }
                    479:
                    480: def test4b() {
                    481:   A=taka_runge_kutta_4a([y1,-y0],x,[y0,y1],3.14,[-1,0],0,0.1);
                    482:   taka_plot_auto(A);
                    483:   return(A);
                    484: }
                    485: endmodule;
                    486:
1.7       takayama  487: import("taka_plot.rr")$
                    488: pari(allocatemem,10^7)$
                    489: module rktest;
                    490: localf re$
                    491: localf re2$
                    492: localf im$
                    493: localf im2$
                    494: localf tryA$
                    495: localf tryA2$
                    496: localf geq$
                    497: localf test1$
                    498:
                    499: def re(L) {
                    500:   return map(re2,L);
                    501: }
                    502: def re2(P) {
                    503:   return map(number_real_part,P);
                    504: }
                    505: def im(L) {
                    506:   return map(im2,L);
                    507: }
                    508: def im2(P) {
                    509:   return map(number_imaginary_part,P);
                    510: }
                    511:
                    512: def geq() {
1.8       takayama  513:   L=x*(1-x)*dx^2+(c-(a+b+1)*x)*dx-a*b;
1.7       takayama  514:   L=base_replace(L,[[a,1/2],[b,1/2],[c,1]]);
                    515:
1.8       takayama  516:   L2 = -((c-(a+b+1)*x)*y2-a*b*y1)/(x*(1-x));
1.7       takayama  517:   L2=base_replace(L2,[[a,1/2],[b,1/2],[c,1]]);
                    518:   return [ y2, L2];
                    519: }
                    520: def tryA() {
                    521:   LL = geq();
                    522:   A = taka_runge_kutta_4_adaptive(
                    523:        LL,
                    524:        x,[y1,y2],
                    525:        0.5+0.5*@i,[-6.78383-1.28991*@i, -1.51159-1.7935*@i],
                    526:        (3-@i)*0.0005, 2.0);
                    527:   taka_plot_auto(re(A));
                    528:   return A;
                    529: }
                    530: def tryA2() {
                    531:   LL = geq();
                    532:   A = taka_runge_kutta_4(
                    533:        LL,
                    534:        x,[y1,y2],
                    535:        0.5+0.5*@i,[-6.78383-1.28991*@i, -1.51159-1.7935*@i],
                    536:        (3-@i)*0.0005, 1.0);
                    537:   taka_plot_auto(re(A));
                    538:   return A;
                    539: }
                    540:
                    541: def test1() {
                    542:   A=tryA2();
                    543:   B=A[100];
                    544:   print(B);
1.10      takayama  545: /* cf. misc-2008/A2/misc/ellip2.m
1.7       takayama  546:   p2 = 0.5+0.5*I --> [-6.78383-1.28991*@i, -1.51159-1.7935*@i].
1.8       takayama  547:   p2 = 0.8495+0.3835*I;
1.7       takayama  548: Print["-------------------"];
                    549: Print[p2];
                    550: Print[N[-2*Gamma[1/2]^2*Hypergeometric2F1[1/2,1/2,1,z] /. {z->p2}]]
                    551: Print[N[D[-2*Gamma[1/2]^2*Hypergeometric2F1[1/2,1/2,1,z],z] /. {z->p2}]]
                    552: */
1.8       takayama  553:  print("math:  [0.8495+0.3835*I, -7.64079 - 2.0799*I, -1.16364 - 4.14709*I] ");
1.10      takayama  554:  print("It was Buggy tryA2() and tryA() --> fixed. see log of 1.8");
1.7       takayama  555: }
                    556:
                    557: endmodule;
                    558:
1.1       takayama  559: end$

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