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2025-02-Numerical/lib/nr/ansi/recipes/sphoot.c
2025-09-12 18:55:25 +09:00

67 lines
1.2 KiB
C

#include <stdio.h>
#define NRANSI
#include "nrutil.h"
#define N2 1
int m,n;
float c2,dx,gmma;
int nvar;
float x1,x2;
int main(void) /* Program sphoot */
{
void newt(float x[], int n, int *check,
void (*vecfunc)(int, float [], float []));
void shoot(int n, float v[], float f[]);
int check,i;
float q1,*v;
v=vector(1,N2);
dx=1.0e-4;
nvar=3;
for (;;) {
printf("input m,n,c-squared\n");
if (scanf("%d %d %f",&m,&n,&c2) == EOF) break;
if (n < m || m < 0) continue;
gmma=1.0;
q1=n;
for (i=1;i<=m;i++) gmma *= -0.5*(n+i)*(q1--/i);
v[1]=n*(n+1)-m*(m+1)+c2/2.0;
x1 = -1.0+dx;
x2=0.0;
newt(v,N2,&check,shoot);
if (check) {
printf("shoot failed; bad initial guess\n");
} else {
printf("\tmu(m,n)\n");
printf("%12.6f\n",v[1]);
}
}
free_vector(v,1,N2);
return 0;
}
void load(float x1, float v[], float y[])
{
float y1 = (n-m & 1 ? -gmma : gmma);
y[3]=v[1];
y[2] = -(y[3]-c2)*y1/(2*(m+1));
y[1]=y1+y[2]*dx;
}
void score(float xf, float y[], float f[])
{
f[1]=(n-m & 1 ? y[1] : y[2]);
}
void derivs(float x, float y[], float dydx[])
{
dydx[1]=y[2];
dydx[2]=(2.0*x*(m+1.0)*y[2]-(y[3]-c2*x*x)*y[1])/(1.0-x*x);
dydx[3]=0.0;
}
#undef N2
#undef NRANSI