media/cast/test/utility/test_util.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include <math.h>
   6
   7 #include <algorithm>
   8
   9 #include "base/strings/stringprintf.h"
  10 #include "media/cast/test/utility/test_util.h"
  11
  12 namespace media {
  13 namespace cast {
  14 namespace test {
  15
  16 MeanAndError::MeanAndError(const std::vector<double>& values) {
  17   double sum = 0.0;
  18   double sqr_sum = 0.0;
  19   num_values = values.size();
  20   if (num_values) {
  21     for (size_t i = 0; i < num_values; i++) {
  22       sum += values[i];
  23       sqr_sum += values[i] * values[i];
  24     }
  25     mean = sum / num_values;
  26     std_dev =
  27         sqrt(std::max(0.0, num_values * sqr_sum - sum * sum)) / num_values;
  28   }
  29 }
  30
  31 std::string MeanAndError::AsString() const {
  32   return base::StringPrintf("%f +/- %f", mean, std_dev);
  33 }
  34
  35 }  // namespace test
  36 }  // namespace cast
  37 }  // namespace media