C语言实现求定积分的方法

#include <cmath> 
#include <cstdio>

 

#define ACC 1000

float solve(float (*p)(float),float up,float down,int acc);
float fun_exp(float x);
float fun_qua(float x);

void main(){

char selection;
float up,down;

while(printf("请选择被积函数:\n"),printf("1、exp(x)   2、x+1 \n"),scanf("%c",&selection),selection != '#'){
printf("请输入积分上下限: ");
scanf("%f,%f",&up,&down);

switch(selection){
case '1':
printf("结果是: %4.4f\n",solve(fun_exp,up,down,ACC));
break;
case '2':
printf("结果是: %4.4f\n",solve(fun_qua,up,down,ACC));
break;
}
}
}

float solve(float (*p)(float),float up,float down,int acc){
float sum,base,area;
area = 0;
sum = 0;
base = (up-down)/acc;

for(int i=0; i
area = base*((*p)(down+i*base));
sum+=area;
}
return sum;
}
float fun_exp(float x){
return exp(x);
}
float fun_qua(float x){ //一元二次方程 quadratics
return x+1;
}