test-ak-sin.cc

#include <AK/Math.h>

#include <float.h>
#include <stdio.h>

float serenity_sin(float f)
{
    return AK::sin(f);
}

#if 1

#include <math.h>

float reference_sin(float f)
{
    return ::sin(f);
}

#else

#include "shared/math.h"

// Use `-I ~/src/llvm-project/libc`.
// Known to be exact for floats: https://members.loria.fr/PZimmermann/papers/accuracy.pdf
float reference_sin(float f)
{
    return LIBC_NAMESPACE::shared::sin(f);
}

#endif

int main()
{
    float f = 0;

    float max_error = 0, max_arg = 0;;

    while (f < 2 * M_PI) {
        float serenity_result = serenity_sin(f);
        float reference_result = reference_sin(f);

        float abs_error = fabs(serenity_result - reference_result);
        if (abs_error > max_error) {
            max_error = abs_error;
            max_arg = f;
        }

        f = nextafterf(f, INFINITY);
    }

    printf("max error: %f\n", max_error);
    printf("AK::sin(%f) = %f\n", max_arg, serenity_sin(max_arg));
    printf("ref sin(%f) = %f\n", max_arg, reference_sin(max_arg));
}