1// Copyright 2017 The TensorFlow Authors. All Rights Reserved. 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14// ============================================================================= 15#ifndef TENSORFLOW_CONTRIB_LIB_UTILS_RANDOM_H_ 16#define TENSORFLOW_CONTRIB_LIB_UTILS_RANDOM_H_ 17 18#include "tensorflow/core/lib/random/simple_philox.h" 19 20namespace tensorflow { 21namespace boosted_trees { 22namespace utils { 23 24// Generates a poisson distributed number with mean 1 for use in bootstrapping. 25inline int32 PoissonBootstrap(random::SimplePhilox* rng) { 26 // Knuth, special cased for lambda = 1.0 for efficiency. 27 static const float lbound = exp(-1.0f); 28 int32 n = 0; 29 for (float r = 1; r > lbound; r *= rng->RandFloat()) { 30 ++n; 31 } 32 return n - 1; 33} 34 35} // namespace utils 36} // namespace boosted_trees 37} // namespace tensorflow 38 39#endif // TENSORFLOW_CONTRIB_LIB_UTILS_RANDOM_H_ 40