Question

C语言：用数值积分的矩形法和梯形法计算(sin x)/x在区间[1，2]上的定积分

急！！！！

Answer 1

#include <stdio.h>
#include <math.h>

double integrate(double (*f)(double),double a,double b)
{
double i=1.0/1000000;
double sum=0,x;
for(x=a;x<=b;)
{
sum+=f(x)*i;
x+=i;
}
return sum;
}

double f(double x)
{
return sin(x)/x;
}

int main()
{
int a=1,b=2;
printf("%lf\n",integrate(f, a, b));
return 0;
}

Answer 2

#include
<stdio.h>
#include
<math.h>
double
integrate(double
(*f)(double),double
a,double
b)
{
double
i=1.0/1000000;
double
sum=0,x;
for(x=a;x<=b;)
{
sum+=f(x)*i;
x+=i;
}
return
sum;
}
double
f(double
x)
{
return
sin(x)/x;
}
int
main()
{
int
a=1,b=2;
printf("%lf
",integrate(f,
a,
b));
return
0;
}