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/*sin,cos,exp函数已经存在于系统的数学函数库中，程序开头需要定义math头文件*/

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#include/****************主函数**************************************/

int main()

{

float integral(float(*)(float), float, float, int);

float fsin(float);

float fcos(float);

float fexp(float);

float a1, b1, a2, b2, a3, b3, c, (*p)(float);//定义一个float类型的指针

int n = 20;

//输入积分上下限

printf("enter a1,b1:\n");

scanf("%f%f", &a1, &b1);

printf("enter a2,b2:\n");

scanf("%f%f", &a2, &b2);

printf("enter a3,b3:\n");

scanf("%f%f", &a3, &b3);

p = fsin;//用float型指针指向fsin函数

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

printf("sin(x)=%f\n", c);

p = fcos;//用float型指针指向fcos函数

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

printf("cos(x)=%f\n", c);

p = fexp;//用float型指针指向exp函数

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

printf("exp(x)=%f\n", c);

return 0;

}

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

{

int i;

float x, h, s;

h = (b - a) / n;//牛顿莱布尼茨公式运用

x = a;

s = 0;

for (i = 0; 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);

}