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/**********************变步长辛普生法*************/ 
/***a为积分下限;b为积分上限;eps为精度要求.********/ 
#include "math.h" 
double bcsimp(a,b,eps) 
double a,b,eps; 
{extern double bcsimpf(); 
int n,k; 
double h,t1,t2,s1,s2,ep,p,x; 
n=1;h=b-a; 
t1=h*(bcsimpf(a)+bcsimpf(b))/2.0; 
s1=t1; 
ep=eps+1.0; 
while(ep>=eps) 
{ 
p=0.0; 
for(k=0;k<=n-1;k++) 
{x=a+(k+0.5)*h; 
p=p+bcsimpf(x); 
} 
t2=(t1+h*p)/2.0; 
s2=(4.0*t2-t1)/3.0; 
ep=fabs(s2-s1); 
t1=t2;s1=s2;n=n+n;h=h/2.0; 
} 
return(s2); 
} 
/*****************************************************************/ 
double bcsimpf(x) 
double x; 
{double y; 
y=exp(x*x); 
return(y); 
} 
/*****************************************************************/ 
main() 
{ 
double a,b,eps,t; 
a=0.0;b=1.0;eps=0.000001; 
t=bcsimp(a,b,eps); 
printf("t=%e\n",t); 
}