yenru0/2025-02-Numerical
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

add numerical recipes library

Browse Source
This commit is contained in:
yenru0
2025-09-12 18:55:25 +09:00
parent d4dff245bd
commit 2c75620ec9
1344 changed files with 63869 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
lib/nr/cpp/recipes/rk4.cpp Normal file
View File

@@ -0,0 +1,25 @@
#include "nr.h"
void NR::rk4(Vec_I_DP &y, Vec_I_DP &dydx, const DP x, const DP h,
Vec_O_DP &yout, void derivs(const DP, Vec_I_DP &, Vec_O_DP &))
{
int i;
DP xh,hh,h6;
int n=y.size();
Vec_DP dym(n),dyt(n),yt(n);
hh=h*0.5;
h6=h/6.0;
xh=x+hh;
for (i=0;i<n;i++) yt[i]=y[i]+hh*dydx[i];
derivs(xh,yt,dyt);
for (i=0;i<n;i++) yt[i]=y[i]+hh*dyt[i];
derivs(xh,yt,dym);
for (i=0;i<n;i++) {
yt[i]=y[i]+h*dym[i];
dym[i] += dyt[i];
}
derivs(x+h,yt,dyt);
for (i=0;i<n;i++)
yout[i]=y[i]+h6*(dydx[i]+dyt[i]+2.0*dym[i]);
}