qtrap1m001.cxx

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

#define N 10000
#define M 100000

typedef double (*dfunc)(double);



static double quad_trap(dfunc f, double a, double b, unsigned int n)
{
    double h = (b - a) / n;
    double res = 0.5 * (f(a) + f(b));
    for (unsigned int i = 1; i < n; i++)
        res += f(a + i * h);

    return res * h;
}

static double f(double x)
{
    return exp(x) - 10.0;
}


int main()
{
    double s = 0;
    for (int i = 0; i < M; i++) {
        s = quad_trap(f, -1.0, 1.0, N);
    }
    printf("%u %u %.18f \n", N, M, s);
    return 0;
}