readme.md

A fast implementation of sin/cos/tan/atan2

Installation

• copy fast_math.h into your project
• add the following line to your CMakeLists.txt

find_package(OpenCV REQUIRED)
target_link_libraries(YOUR_PROJECT ${OpenCV_LIBS})

Usage

#include "fast_math.h"

int main()
{
    FastMath::sin(1);
    FastMath::cos(1);
    FastMath::tan(1);
    auto [s, c] = FastMath::sincos(1);
    FastMath::atan2(1, 1);
}

Benchmark

• about 4x ~ 7x faster than std math function

---------------------------------------------------------
Benchmark               Time             CPU   Iterations
---------------------------------------------------------
TestFastTan        144015 ns       144012 ns         4866
TestSTDTan         587773 ns       587760 ns         1190
TestFastSin        144189 ns       144187 ns         4857
TestSTDSin         617861 ns       617853 ns         1133
TestFastCos        143166 ns       143163 ns         4889
TestSTDCos         632660 ns       632646 ns         1106
TestFastSinCos     144369 ns       144363 ns         4842
TestSTDSinCos      956463 ns       956441 ns          732

Accuracy

Function	Max Absolute Error	Max Relative Error
sin	1e-5	not tested
cos	1e-5	not tested
sincos	1e-5	not tested
tan	1e-5 when abs(deg) belong [-89.9 ± n x 180, 89.9 ± n x 180]	not tested
tan	not tested	1e-5 when abs(deg) belong [-89.999 ± n x 180, 89.999 ± n x 180]
atan2	not tested	not tested

Reference

• Qt
• OpenCV