Loading [MathJax]/extensions/tex2jax.js
LSST Applications g04a91732dc+2945638123,g07dc498a13+7e3c5f68a2,g12483e3c20+e0fa9c8503,g1409bbee79+7e3c5f68a2,g1a7e361dbc+7e3c5f68a2,g1fd858c14a+9f35e23ec3,g35bb328faa+fcb1d3bbc8,g3ad4f90e5c+e0fa9c8503,g3bd4b5ce2c+36fb6ead7f,g4e0f332c67+5d362be553,g53246c7159+fcb1d3bbc8,g5477a8d5ce+db04660fe6,g60b5630c4e+e0fa9c8503,g75b6c65c88+55830bd904,g78460c75b0+2f9a1b4bcd,g786e29fd12+cf7ec2a62a,g7b71ed6315+fcb1d3bbc8,g8852436030+4639f750a5,g89139ef638+7e3c5f68a2,g8f1d76f86f+11a01f47f4,g9125e01d80+fcb1d3bbc8,g919ac25b3e+28db628500,g95236ca021+f7a31438ed,g989de1cb63+7e3c5f68a2,g9f33ca652e+d1e6496fea,ga365f290ef+26a6f9aaf0,gaaedd4e678+7e3c5f68a2,gabe3b4be73+1e0a283bba,gb1101e3267+c09b629e83,gb4a253aaf5+0122250889,gb58c049af0+f03b321e39,gbaa7868d32+e0fa9c8503,gc99c83e5f0+76d20ab76d,gcf25f946ba+4639f750a5,gd6cbbdb0b4+c8606af20c,gde0f65d7ad+021d0de224,ge278dab8ac+932305ba37,gfba249425e+fcb1d3bbc8,w.2025.08
LSST Data Management Base Package
All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Properties Friends Macros Modules Pages
SafeSum.h
Go to the documentation of this file.
1// -*- LSST-C++ -*-
2/*
3 * Developed for the LSST Data Management System.
4 * This product includes software developed by the LSST Project
5 * (https://www.lsst.org).
6 * See the COPYRIGHT file at the top-level directory of this distribution
7 * for details of code ownership.
8 *
9 * This program is free software: you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation, either version 3 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program. If not, see <https://www.gnu.org/licenses/>.
21 */
22#ifndef LSST_AFW_MATH_POLYNOMIALS_SafeSum_h_INCLUDED
23#define LSST_AFW_MATH_POLYNOMIALS_SafeSum_h_INCLUDED
24
25#include <cmath>
26
27namespace lsst { namespace geom { namespace polynomials {
28
32enum class SumMode {
37};
38
61template <typename T>
62class SafeSum {
63public:
64
65 explicit SafeSum(T initial=static_cast<T>(0)) noexcept :
66 _sum(initial),
67 _correction(static_cast<T>(0))
68 {}
69
70 SafeSum & operator=(T value) noexcept {
71 _sum = value;
72 _correction = static_cast<T>(0);
73 return *this;
74 }
75
76 SafeSum & operator+=(T value) noexcept {
77 T t = _sum + value;
78 // update _correction to account for lost low-order bits of the
79 // greater of _sum and value
80 if (std::abs(_sum) >= std::abs(value)) {
81 _correction += (_sum - t) + value;
82 } else {
83 _correction += (value - t) + _sum;
84 }
85 _sum = t;
86 return *this;
87 }
88
89 SafeSum & operator-=(T value) noexcept {
90 return operator+=(-value);
91 }
92
93 explicit operator T() const noexcept {
94 return _sum + _correction;
95 }
96
97private:
98 T _sum;
99 T _correction;
100};
101
102}}} // namespace lsst::geom::polynomials
103
104#endif // !LSST_AFW_MATH_POLYNOMIALS_SafeSum_h_INCLUDED
SafeSum & operator-=(T value) noexcept
Definition SafeSum.h:89
SafeSum & operator+=(T value) noexcept
Definition SafeSum.h:76
SafeSum(T initial=static_cast< T >(0)) noexcept
Definition SafeSum.h:65
SafeSum & operator=(T value) noexcept
Definition SafeSum.h:70
Low-level polynomials (including special polynomials) in C++.
SumMode
Enum used to control how to sum polynomial terms.
Definition SafeSum.h:32
@ SAFE
Compensated summation using SafeSum. Involves ~4x as many floating point operations.
Definition SafeSum.h:36
@ FAST
Summation using regular floating-point addition.
Definition SafeSum.h:34