C语言中矩形公式计算定积分的通用函数实现

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

double integral(double (*f)(double), double a, double b);

double f_sin(double x); double f_cos(double x); double f_exp(double x);

int main() { double a, b; scanf("%lf %lf", &a, &b); printf("%.6f %.6f %.6f", integral(f_sin, a, b), integral(f_cos, a, b), integral(f_exp, a, b)); return 0; }

double integral(double (*f)(double), double a, double b) { double h = (b - a) / 1000.0; double s = 0.0; for (int i = 0; i < 1000; i++) { s += f(a + (i + 0.5) * h) * h; } return s; }

double f_sin(double x) { return sin(x); }

double f_cos(double x) { return cos(x); }

double f_exp(double x) { return exp(x); }