37 lines
638 B
C++
37 lines
638 B
C++
#include "nr.h"
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extern Vec_DP *xx_p;
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extern Mat_DP *y_p;
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void NR::rkdumb(Vec_I_DP &vstart, const DP x1, const DP x2,
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void derivs(const DP, Vec_I_DP &, Vec_O_DP &))
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{
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int i,k;
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DP x,h;
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Vec_DP &xx=*xx_p;
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Mat_DP &y=*y_p;
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int nvar=y.nrows();
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int nstep=y.ncols()-1;
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Vec_DP v(nvar),vout(nvar),dv(nvar);
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for (i=0;i<nvar;i++) {
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v[i]=vstart[i];
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y[i][0]=v[i];
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}
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xx[0]=x1;
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x=x1;
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h=(x2-x1)/nstep;
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for (k=0;k<nstep;k++) {
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derivs(x,v,dv);
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rk4(v,dv,x,h,vout,derivs);
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if (x+h == x)
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nrerror("Step size too small in routine rkdumb");
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x += h;
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xx[k+1]=x;
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for (i=0;i<nvar;i++) {
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v[i]=vout[i];
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y[i][k+1]=v[i];
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}
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}
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}
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