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37 #ifndef GMX_MATH_UTILITIES_H
38 #define GMX_MATH_UTILITIES_H
40 #include "../legacyheaders/types/simple.h"
48 #define M_PI 3.14159265358979323846
52 #define M_PI_2 1.57079632679489661923
56 #define M_2PI 6.28318530717958647692
60 #define M_SQRT2 sqrt(2.0)
64 #define M_1_PI 0.31830988618379067154
67 #ifndef M_FLOAT_1_SQRTPI /* used in CUDA kernels */
68 /* 1.0 / sqrt(M_PI) */
69 #define M_FLOAT_1_SQRTPI 0.564189583547756f
73 /* 1.0 / sqrt(M_PI) */
74 #define M_1_SQRTPI 0.564189583547756
78 /* 2.0 / sqrt(M_PI) */
79 #define M_2_SQRTPI 1.128379167095513
83 real sign(real x, real y);
85 real cuberoot (real a);
86 double gmx_erfd(double x);
87 double gmx_erfcd(double x);
88 float gmx_erff(float x);
89 float gmx_erfcf(float x);
91 #define gmx_erf(x) gmx_erfd(x)
92 #define gmx_erfc(x) gmx_erfcd(x)
94 #define gmx_erf(x) gmx_erff(x)
95 #define gmx_erfc(x) gmx_erfcf(x)
98 gmx_bool gmx_isfinite(real x);
99 gmx_bool gmx_isnan(real x);
101 /*! \brief Check if two numbers are within a tolerance
103 * This routine checks if the relative difference between two numbers is
104 * approximately within the given tolerance, defined as
105 * fabs(f1-f2)<=tolerance*fabs(f1+f2).
107 * To check if two floating-point numbers are almost identical, use this routine
108 * with the tolerance GMX_REAL_EPS, or GMX_DOUBLE_EPS if the check should be
109 * done in double regardless of Gromacs precision.
111 * To check if two algorithms produce similar results you will normally need
112 * to relax the tolerance significantly since many operations (e.g. summation)
113 * accumulate floating point errors.
115 * \param f1 First number to compare
116 * \param f2 Second number to compare
117 * \param tol Tolerance to use
119 * \return 1 if the relative difference is within tolerance, 0 if not.
122 gmx_within_tol(double f1,
127 * \brief Check if a number is smaller than some preset safe minimum
128 * value, currently defined as GMX_REAL_MIN/GMX_REAL_EPS.
130 * If a number is smaller than this value we risk numerical overflow
131 * if any number larger than 1.0/GMX_REAL_EPS is divided by it.
133 * \return 1 if 'almost' numerically zero, 0 otherwise.
136 gmx_numzero(double a);
138 /*! \brief Compute floor of logarithm to base 2
143 gmx_log2i(unsigned int x);
145 /*! /brief Multiply two large ints
147 * \return False iff overflow occured
150 check_int_multiply_for_overflow(gmx_int64_t a,
152 gmx_int64_t *result);
154 /*! \brief Find greatest common divisor of two numbers
156 * \return GCD of the two inputs
159 gmx_greatest_common_divisor(int p, int q);