r-k.c

计算方法的几个经典算法

#define f(t,y) (y-(2*t)/y)
#define MAX 500
#include<stdio.h>
int main()
{
	int n,i;
	double a,b,alpha;
	double h,t,w;
	double k1,k2,k3,k4;
	printf("input the a,b:\n");

	scanf("%lf%lf",&a,&b);
	printf("now please input the alpha:\n");
	scanf("%lf",&alpha);
	printf("please input the n:\n");
	scanf("%d",&n);
	h=(b-a)/n;
	t=a;
	w=alpha;
	for(i=1;i<=n;i++){
		k1=h*f(t,w);
		k2=h*f((t+h/2),(w+k1/2));
		k3=h*f((t+h/2),(w+k2/2));
		k3=h*f((t+h/2),(w+k2/2));
		k4=h*f((t+h),(w+k3));
		w=w+(k1+2*k2+2*k3+k4)/6;
		t=a+i*h;
		printf("t%d=%lf,y%d=%lf\n",i,t,i,w);
	}
	return 0;
}