用矩形法求定积分的通用函数

解： #include

main()

{ float integral(float(8p)(float),float a,float b,int n);

float a1,b1,a2,b2,a3,b3,c,(*p)(float);

float fsin(float);

float fcos(float);

float fexp(float);

int n=20;

printf(“Input a1,b1:”);

scanf(“%f,%f”,&a1,&b2);

printf(“Input a2,b2:”);

scanf(“%f,%f”,&a2,&b2);

printf(“Input a3,b3:”);

scanf(“%f,%f”,&a3,b3);

p=fsin;

c=integral(p,a1,b1,n);

printf(“The integral of sin(x) is:%fn”,c);

p=fcos;

c=integral(p,a2,b2,n);

printf(“The integral of cos(x) is :%fn”,c);

c=integral(p,a3,b3,n);

printf(“The integral of sin(x) is :%fn”,c);

}

float integral(float (*p)(float),float a,float b,int n)

{

int i;

floatx,h,s;

h=(b-a)/n;

x=a;

s=0;

for(i=1;i<=n;i++)

{x=x+h;

s=s+(*p)(x)*h;

}

return(s);

}

float fsin(float x)

{return sin(x);}

float fcos(float x)

{return cos(x);}

float fexp(float x)

{return exp(x);}