37 lines
739 B
C++
37 lines
739 B
C++
#include "nr.h"
|
|
|
|
void NR::voltra(const DP t0, const DP h, Vec_O_DP &t, Mat_O_DP &f,
|
|
DP g(const int, const DP),
|
|
DP ak(const int, const int, const DP, const DP))
|
|
{
|
|
int i,j,k,l;
|
|
DP d,sum;
|
|
|
|
int m=f.nrows();
|
|
int n=f.ncols();
|
|
Vec_INT indx(m);
|
|
Vec_DP b(m);
|
|
Mat_DP a(m,m);
|
|
t[0]=t0;
|
|
for (k=0;k<m;k++) f[k][0]=g(k,t[0]);
|
|
for (i=1;i<n;i++) {
|
|
t[i]=t[i-1]+h;
|
|
for (k=0;k<m;k++) {
|
|
sum=g(k,t[i]);
|
|
for (l=0;l<m;l++) {
|
|
sum += 0.5*h*ak(k,l,t[i],t[0])*f[l][0];
|
|
for (j=1;j<i;j++)
|
|
sum += h*ak(k,l,t[i],t[j])*f[l][j];
|
|
if (k == l)
|
|
a[k][l]=1.0-0.5*h*ak(k,l,t[i],t[i]);
|
|
else
|
|
a[k][l] = -0.5*h*ak(k,l,t[i],t[i]);
|
|
}
|
|
b[k]=sum;
|
|
}
|
|
ludcmp(a,indx,d);
|
|
lubksb(a,indx,b);
|
|
for (k=0;k<m;k++) f[k][i]=b[k];
|
|
}
|
|
}
|