pow10_helper.h (1399B)
1 // 2 // Copyright 2018 The Abseil Authors. 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // https://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 // 16 // This test helper library contains a table of powers of 10, to guarantee 17 // precise values are computed across the full range of doubles. We can't rely 18 // on the pow() function, because not all standard libraries ship a version 19 // that is precise. 20 #ifndef ABSL_STRINGS_INTERNAL_POW10_HELPER_H_ 21 #define ABSL_STRINGS_INTERNAL_POW10_HELPER_H_ 22 23 #include <vector> 24 25 #include "absl/base/config.h" 26 27 namespace absl { 28 ABSL_NAMESPACE_BEGIN 29 namespace strings_internal { 30 31 // Computes the precise value of 10^exp. (I.e. the nearest representable 32 // double to the exact value, rounding to nearest-even in the (single) case of 33 // being exactly halfway between.) 34 double Pow10(int exp); 35 36 } // namespace strings_internal 37 ABSL_NAMESPACE_END 38 } // namespace absl 39 40 #endif // ABSL_STRINGS_INTERNAL_POW10_HELPER_H_