Fast Math C

Fast Math C is a lightweight C library for fast evaluation of mathematical functions using precomputed lookup tables and linear interpolation. It is designed to accelerate repeated function calls (such as tanh, inv, etc.) over a specified range, trading a small amount of memory for significant speed improvements.

Features

• Precompute function values over a user-defined range and sample count.
• Fast evaluation using linear interpolation.
• Supports any single-argument float function.
• Simple API for initialization and querying.

Usage

#include "fast_math.h"
#include <math.h>

// Define your function
float inv(float x) {
    if (x == 0.f) return 0.f;
    return 1.f / x;
}

int main() {
    // Initialize lookup for inv(x) over [-3, 3] with 2137 samples
    fast_math_function_t inv_struct = fast_math_init(inv, -3.f, 3.f, 2137);
    printf("1 / 0.1 = %f\n", fast_math_get(0.1f, &inv_struct));

    // Initialize lookup for tanh(x) over [-4, 4] with 4096 samples
    fast_math_function_t tanh_struct = fast_math_init(tanhf, -4.f, 4.f, 4096);
    printf("tanh(0.1) = %f\n", fast_math_get(0.1f, &tanh_struct));
}

API

• fast_math_function_t fast_math_init(float (*target_function)(float), float start_value, float end_value, int32_t samples_n);
  • Initializes a lookup table for the given function.
• float fast_math_get(float x, fast_math_function_t* fast_math_struct);
  • Retrieves the interpolated function value for x.

Files

• fast_math.c / fast_math.h: Library implementation and API.
• main.c: Example usage.

License

MIT