chromium/third_party/google_benchmark/src/src/complexity.cc

// Copyright 2016 Ismael Jimenez Martinez. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Source project : https://github.com/ismaelJimenez/cpp.leastsq
// Adapted to be used with google benchmark

#include "complexity.h"

#include <algorithm>
#include <cmath>

#include "benchmark/benchmark.h"
#include "check.h"

namespace benchmark {

// Internal function to calculate the different scalability forms
BigOFunc* FittingCurve(BigO complexity) { … }

// Function to return an string for the calculated complexity
std::string GetBigOString(BigO complexity) { … }

// Find the coefficient for the high-order term in the running time, by
// minimizing the sum of squares of relative error, for the fitting curve
// given by the lambda expression.
//   - n             : Vector containing the size of the benchmark tests.
//   - time          : Vector containing the times for the benchmark tests.
//   - fitting_curve : lambda expression (e.g. [](int64_t n) {return n; };).

// For a deeper explanation on the algorithm logic, please refer to
// https://en.wikipedia.org/wiki/Least_squares#Least_squares,_regression_analysis_and_statistics

LeastSq MinimalLeastSq(const std::vector<int64_t>& n,
                       const std::vector<double>& time,
                       BigOFunc* fitting_curve) { … }

// Find the coefficient for the high-order term in the running time, by
// minimizing the sum of squares of relative error.
//   - n          : Vector containing the size of the benchmark tests.
//   - time       : Vector containing the times for the benchmark tests.
//   - complexity : If different than oAuto, the fitting curve will stick to
//                  this one. If it is oAuto, it will be calculated the best
//                  fitting curve.
LeastSq MinimalLeastSq(const std::vector<int64_t>& n,
                       const std::vector<double>& time, const BigO complexity) { … }

std::vector<BenchmarkReporter::Run> ComputeBigO(
    const std::vector<BenchmarkReporter::Run>& reports) { … }

}  // end namespace benchmark