MathApproxTest.cpp

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/*  SPDX-License-Identifier: GPL-2.0-or-later */
/*!********************************************************************
 
  Audacity: A Digital Audio Editor
 
  MathApproxTest.cpp
 
  Matthieu Hodgkinson
 
**********************************************************************/
 
#include "MathApprox.h"
#include <catch2/catch.hpp>
#include <numeric>
 
TEST_CASE("FastLog2")
{
   constexpr auto size = 40;
   const auto input = [&] {
      std::vector<float> exponential(size);
      std::iota(exponential.begin(), exponential.end(), -20.f);
      std::vector<float> input(exponential.size());
      std::transform(
         exponential.begin(), exponential.end(), input.begin(),
         [](float x) { return std::exp(x); });
      return input;
   }();
   const auto expected = [&] {
      std::vector<float> expected(size);
      std::transform(input.begin(), input.end(), expected.begin(), [](float x) {
         return std::log2(x);
      });
      return expected;
   }();
   const auto actual = [&] {
      std::vector<float> actual(size);
      std::transform(input.begin(), input.end(), actual.begin(), FastLog2);
      return actual;
   }();
   const auto error = [&] {
      std::vector<float> error(size);
      std::transform(
         expected.begin(), expected.end(), actual.begin(), error.begin(),
         [](float e, float a) { return std::abs(e - a); });
      return error;
   }();
   const auto maxError = *std::max_element(error.begin(), error.end());
   REQUIRE(maxError < 1e-2);
}