Opencv中新增的数学函数

opencv中也新增了一些数学函数，有cubeRoot、fastAtan2、cvFloor、cvRound、cvCeil、cvIsInf、cvIsNan等

cubeRoot函数原型：

用于计算立方根

/** @brief Computes the cube root of an argument.

The function cubeRoot computes \f$\sqrt[3]{\texttt{val}}\f$. Negative arguments are handled correctly.

NaN and Inf are not handled. The accuracy approaches the maximum possible accuracy for

single-precision data.

@param val A function argument.

CV_EXPORTS_W float cubeRoot(float val);

fastAtan2函数原型：

用于向量角度计算

/** @brief Calculates the angle of a 2D vector in degrees.

The function fastAtan2 calculates the full-range angle of an input 2D vector. The angle is measured

in degrees and varies from 0 to 360 degrees. The accuracy is about 0.3 degrees.

@param x x-coordinate of the vector.

@param y y-coordinate of the vector.

CV_EXPORTS_W float fastAtan2(float y, float x);

两函数测试代码：

float t = fastAtan2(2, 3);

printf("向量角度：%f\n", t);

float r = cubeRoot(13);

printf("开立方根结果：%f\n", r);

两函数测试结果：

1 2	向量角度：33.683205 开立方根结果：2.351335

除了以上函数，opencv还定义了一些新数学函数，都在fast_math.hpp头文件中

新增定义函数有：

CV_INLINE int cvRound( double value ) //四舍五入函数

CV_INLINE int cvFloor( double value ) //向下取整

CV_INLINE int cvCeil( double value ) //向上取整

CV_INLINE int cvIsNaN( double value ) //判断是否是一个数

CV_INLINE int cvIsInf( double value ) //判断是否无穷大

CV_INLINE int cvRound(float value)

CV_INLINE int cvRound( int value )

CV_INLINE int cvFloor( float value )

CV_INLINE int cvFloor( int value )

CV_INLINE int cvCeil( float value )

CV_INLINE int cvCeil( int value )

CV_INLINE int cvIsNaN( float value )

CV_INLINE int cvIsInf( float value )

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/*M///////////////////////////////////////////////////////////////////////////////////////

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//M*/

#ifndef OPENCV_CORE_FAST_MATH_HPP

#define OPENCV_CORE_FAST_MATH_HPP

#include "opencv2/core/cvdef.h"

#if ((defined _MSC_VER && defined _M_X64) || (defined __GNUC__ && defined __x86_64__ \

&& defined __SSE2__ && !defined __APPLE__)) && !defined(__CUDACC__)

#include <emmintrin.h>

#endif

//! @addtogroup core_utils

//! @{

/****************************************************************************************\

* fast math *

\****************************************************************************************/

#ifdef __cplusplus

# include <cmath>

#else

# ifdef __BORLANDC__

# include <fastmath.h>

# else

# include <math.h>

# endif

#endif

#ifdef HAVE_TEGRA_OPTIMIZATION

# include "tegra_round.hpp"

#endif

#if defined __GNUC__ && defined __arm__ && (defined __ARM_PCS_VFP || defined __ARM_VFPV3__ || defined __ARM_NEON__) && !defined __SOFTFP__ && !defined(__CUDACC__)

// 1. general scheme

#define ARM_ROUND(_value, _asm_string) \

int res; \

float temp; \

CV_UNUSED(temp); \

__asm__(_asm_string : [res] "=r" (res), [temp] "=w" (temp) : [value] "w" (_value)); \

return res

// 2. version for double

#ifdef __clang__

#define ARM_ROUND_DBL(value) ARM_ROUND(value, "vcvtr.s32.f64 %[temp], %[value] \n vmov %[res], %[temp]")

#else

#define ARM_ROUND_DBL(value) ARM_ROUND(value, "vcvtr.s32.f64 %[temp], %P[value] \n vmov %[res], %[temp]")

#endif

// 3. version for float

#define ARM_ROUND_FLT(value) ARM_ROUND(value, "vcvtr.s32.f32 %[temp], %[value]\n vmov %[res], %[temp]")

#endif

/** @brief Rounds floating-point number to the nearest integer

@param value floating-point number. If the value is outside of INT_MIN ... INT_MAX range, the

result is not defined.

CV_INLINE int

cvRound( double value )

{

#if ((defined _MSC_VER && defined _M_X64) || (defined __GNUC__ && defined __x86_64__ \

&& defined __SSE2__ && !defined __APPLE__) || CV_SSE2) && !defined(__CUDACC__)

__m128d t = _mm_set_sd( value );

return _mm_cvtsd_si32(t);

#elif defined _MSC_VER && defined _M_IX86

int t;

__asm

{

fld value;

fistp t;

}

return t;

#elif ((defined _MSC_VER && defined _M_ARM) || defined CV_ICC || \

defined __GNUC__) && defined HAVE_TEGRA_OPTIMIZATION

TEGRA_ROUND_DBL(value);

#elif defined CV_ICC || defined __GNUC__

# if defined ARM_ROUND_DBL

ARM_ROUND_DBL(value);

# else

return (int)lrint(value);

# endif

#else

/* it's ok if round does not comply with IEEE754 standard;

the tests should allow +/-1 difference when the tested functions use round */

return (int)(value + (value >= 0 ? 0.5 : -0.5));

#endif

}

/** @brief Rounds floating-point number to the nearest integer not larger than the original.

The function computes an integer i such that:

\f[i \le \texttt{value} < i+1\f]

@param value floating-point number. If the value is outside of INT_MIN ... INT_MAX range, the

result is not defined.

CV_INLINE int cvFloor( double value )

{

int i = (int)value;

return i - (i > value);

}

/** @brief Rounds floating-point number to the nearest integer not smaller than the original.

The function computes an integer i such that:

\f[i \le \texttt{value} < i+1\f]

@param value floating-point number. If the value is outside of INT_MIN ... INT_MAX range, the

result is not defined.

CV_INLINE int cvCeil( double value )

{

int i = (int)value;

return i + (i < value);

}

/** @brief Determines if the argument is Not A Number.

@param value The input floating-point value

The function returns 1 if the argument is Not A Number (as defined by IEEE754 standard), 0

otherwise. */

CV_INLINE int cvIsNaN( double value )

{

Cv64suf ieee754;

ieee754.f = value;

return ((unsigned)(ieee754.u >> 32) & 0x7fffffff) +

((unsigned)ieee754.u != 0) > 0x7ff00000;

}

/** @brief Determines if the argument is Infinity.

@param value The input floating-point value

The function returns 1 if the argument is a plus or minus infinity (as defined by IEEE754 standard)

and 0 otherwise. */

CV_INLINE int cvIsInf( double value )

{

Cv64suf ieee754;

ieee754.f = value;

return ((unsigned)(ieee754.u >> 32) & 0x7fffffff) == 0x7ff00000 &&

(unsigned)ieee754.u == 0;

}

#ifdef __cplusplus

/** @overload */

CV_INLINE int cvRound(float value)

{

#if ((defined _MSC_VER && defined _M_X64) || (defined __GNUC__ && defined __x86_64__ \

&& defined __SSE2__ && !defined __APPLE__) || CV_SSE2) && !defined(__CUDACC__)

__m128 t = _mm_set_ss( value );

return _mm_cvtss_si32(t);

#elif defined _MSC_VER && defined _M_IX86

int t;

__asm

{

fld value;

fistp t;

}

return t;

#elif ((defined _MSC_VER && defined _M_ARM) || defined CV_ICC || \

defined __GNUC__) && defined HAVE_TEGRA_OPTIMIZATION

TEGRA_ROUND_FLT(value);

#elif defined CV_ICC || defined __GNUC__

# if defined ARM_ROUND_FLT

ARM_ROUND_FLT(value);

# else

return (int)lrintf(value);

# endif

#else

/* it's ok if round does not comply with IEEE754 standard;

the tests should allow +/-1 difference when the tested functions use round */

return (int)(value + (value >= 0 ? 0.5f : -0.5f));

#endif

}

/** @overload */

CV_INLINE int cvRound( int value )

{

return value;

}

/** @overload */

CV_INLINE int cvFloor( float value )

{

int i = (int)value;

return i - (i > value);

}

/** @overload */

CV_INLINE int cvFloor( int value )

{

return value;

}

/** @overload */

CV_INLINE int cvCeil( float value )

{

int i = (int)value;

return i + (i < value);

}

/** @overload */

CV_INLINE int cvCeil( int value )

{

return value;

}

/** @overload */

CV_INLINE int cvIsNaN( float value )

{

Cv32suf ieee754;

ieee754.f = value;

return (ieee754.u & 0x7fffffff) > 0x7f800000;

}

/** @overload */

CV_INLINE int cvIsInf( float value )

{

Cv32suf ieee754;

ieee754.f = value;

return (ieee754.u & 0x7fffffff) == 0x7f800000;

}

#endif // __cplusplus

//! @} core_utils

#endif

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