backend/nsl/nsl_math.h

0001 /***************************************************************************
0002     File                 : nsl_math.h
0003     Project              : LabPlot
0004     Description          : NSL math functions
0005     --------------------------------------------------------------------
0006     Copyright            : (C) 2018-2020 by Stefan Gerlach (stefan.gerlach@uni.kn)
0007
0008  ***************************************************************************/
0009
0010 /***************************************************************************
0011  *                                                                         *
0012  *  This program is free software; you can redistribute it and/or modify   *
0013  *  it under the terms of the GNU General Public License as published by   *
0014  *  the Free Software Foundation; either version 2 of the License, or      *
0015  *  (at your option) any later version.                                    *
0016  *                                                                         *
0017  *  This program is distributed in the hope that it will be useful,        *
0018  *  but WITHOUT ANY WARRANTY; without even the implied warranty of         *
0019  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          *
0020  *  GNU General Public License for more details.                           *
0021  *                                                                         *
0022  *   You should have received a copy of the GNU General Public License     *
0023  *   along with this program; if not, write to the Free Software           *
0024  *   Foundation, Inc., 51 Franklin Street, Fifth Floor,                    *
0025  *   Boston, MA  02110-1301  USA                                           *
0026  *                                                                         *
0027  ***************************************************************************/
0028
0029 #ifndef NSL_MATH_H
0030 #define NSL_MATH_H
0031
0032 #include <stdbool.h>
0033
0034 #define M_PI_180 (M_PI/180.)
0035 #define M_180_PI (180./M_PI)
0036
0037 /*
0038  * more intelligent comparison of doubles,
0039  * taken from Knuth's "The art of computer programming"
0040  */
0041 bool nsl_math_approximately_equal(double a, double b);
0042 bool nsl_math_essentially_equal(double a, double b);
0043 bool nsl_math_definitely_greater_than(double a, double b);
0044 bool nsl_math_definitely_less_than(double a, double b);
0045 bool nsl_math_approximately_equal_eps(double a, double b, double epsilon);
0046 bool nsl_math_essentially_equal_eps(double a, double b, double epsilon);
0047 bool nsl_math_definitely_greater_than_eps(double a, double b, double epsilon);
0048 bool nsl_math_definitely_less_than_eps(double a, double b, double epsilon);
0049
0050 /* returns decimal places of signed value
0051 * 0.1 -> 1, 0.06 -> 2, 23 -> -1, 100 -> -2
0052 */
0053 int nsl_math_decimal_places(double value);
0054
0055 /* return decimal places of signed value rounded to one digit
0056 * 0.1 -> 1, 0.006 -> 2, 0.8 -> 0, 12 -> -1, 520 -> -3
0057 */
0058 int nsl_math_rounded_decimals(double value);
0059
0060 /* nsl_math_rounded_decimals() but max 'max'
0061  */
0062 int nsl_math_rounded_decimals_max(double value, int max);
0063
0064 /* round double value to n decimal places */
0065 double nsl_math_round_places(double value, unsigned int n);
0066
0067 /* round double value to precision p */
0068 double nsl_math_round_precision(double value, unsigned int p);
0069
0070 #endif /* NSL_MATH_H */