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#pragma once
#include <util/system/yassert.h>
#include <util/system/defaults.h>
#include <cmath>
#include <cfloat>
#include <cstdlib>
#include "typetraits.h"
#include "utility.h"
constexpr double PI = M_PI;
constexpr double M_LOG2_10 = 3.32192809488736234787; // log2(10)
constexpr double M_LN2_INV = M_LOG2E; // 1 / ln(2) == log2(e)
/**
* \returns Absolute value of the provided argument.
*/
template <class T>
constexpr T Abs(T value) {
return std::abs(value);
}
/**
* @returns Base 2 logarithm of the provided double
* precision floating point value.
*/
inline double Log2(double value) {
return log(value) * M_LN2_INV;
}
/**
* @returns Base 2 logarithm of the provided
* floating point value.
*/
inline float Log2(float value) {
return logf(value) * static_cast<float>(M_LN2_INV);
}
/**
* @returns Base 2 logarithm of the provided integral value.
*/
template <class T>
inline std::enable_if_t<std::is_integral<T>::value, double>
Log2(T value) {
return Log2(static_cast<double>(value));
}
/** Returns 2^x */
double Exp2(double);
float Exp2f(float);
template <class T>
static constexpr T Sqr(const T t) noexcept {
return t * t;
}
inline double Sigmoid(double x) {
return 1.0 / (1.0 + std::exp(-x));
}
inline float Sigmoid(float x) {
return 1.0f / (1.0f + std::exp(-x));
}
static inline bool IsFinite(double f) {
#if defined(isfinite)
return isfinite(f);
#elif defined(_win_)
return _finite(f) != 0;
#elif defined(_darwin_)
return isfinite(f);
#elif defined(__GNUC__)
return __builtin_isfinite(f);
#elif defined(_STLP_VENDOR_STD)
return _STLP_VENDOR_STD::isfinite(f);
#else
return std::isfinite(f);
#endif
}
static inline bool IsNan(double f) {
#if defined(_win_)
return _isnan(f) != 0;
#else
return std::isnan(f);
#endif
}
inline bool IsValidFloat(double f) {
return IsFinite(f) && !IsNan(f);
}
#ifdef _MSC_VER
double Erf(double x);
#else
inline double Erf(double x) {
return erf(x);
}
#endif
/**
* @returns Natural logarithm of the absolute value
* of the gamma function of provided argument.
*/
inline double LogGamma(double x) noexcept {
#if defined(_glibc_)
int sign;
(void)sign;
return lgamma_r(x, &sign);
#elif defined(__GNUC__)
return __builtin_lgamma(x);
#elif defined(_unix_)
return lgamma(x);
#else
extern double LogGammaImpl(double);
return LogGammaImpl(x);
#endif
}
/**
* @returns x^n for integer n, n >= 0.
*/
template <class T, class Int>
T Power(T x, Int n) {
static_assert(std::is_integral<Int>::value, "only integer powers are supported");
Y_ASSERT(n >= 0);
if (n == 0) {
return T(1);
}
while ((n & 1) == 0) {
x = x * x;
n >>= 1;
}
T result = x;
n >>= 1;
while (n > 0) {
x = x * x;
if (n & 1) {
result = result * x;
}
n >>= 1;
}
return result;
};
/**
* Compares two floating point values and returns true if they are considered equal.
* The two numbers are compared in a relative way, where the exactness is stronger
* the smaller the numbers are.
*
* Note that comparing values where either one is 0.0 will not work.
* The solution to this is to compare against values greater than or equal to 1.0.
*
* @code
* // Instead of comparing with 0.0
* FuzzyEquals(0.0, 1.0e-200); // This will return false
* // Compare adding 1 to both values will fix the problem
* FuzzyEquals(1 + 0.0, 1 + 1.0e-200); // This will return true
* @endcode
*/
inline bool FuzzyEquals(double p1, double p2, double eps = 1.0e-13) {
return (Abs(p1 - p2) <= eps * Min(Abs(p1), Abs(p2)));
}
/**
* @see FuzzyEquals(double, double, double)
*/
inline bool FuzzyEquals(float p1, float p2, float eps = 1.0e-6) {
return (Abs(p1 - p2) <= eps * Min(Abs(p1), Abs(p2)));
}
namespace NUtilMathPrivate {
template <bool IsSigned>
struct TCeilDivImpl {};
template <>
struct TCeilDivImpl<true> {
template <class T>
static inline T Do(T x, T y) noexcept {
return x / y + (((x < 0) ^ (y > 0)) && (x % y));
}
};
template <>
struct TCeilDivImpl<false> {
template <class T>
static inline T Do(T x, T y) noexcept {
auto quot = x / y;
return (x % y) ? (quot + 1) : quot;
}
};
}
/**
* @returns Equivalent to ceil((double) x / (double) y) but using only integer arithmetic operations
*/
template <class T>
inline T CeilDiv(T x, T y) noexcept {
static_assert(std::is_integral<T>::value, "Integral type required.");
Y_ASSERT(y != 0);
return ::NUtilMathPrivate::TCeilDivImpl<std::is_signed<T>::value>::Do(x, y);
}
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