ccgl::utils_math Namespace Reference

Basic mathematics related functions. More...

Functions
template<typename T1 , typename T2 >
bool	FloatEqual (T1 v1, T2 v2)
	Whether v1 is equal to v2. More...
float	Expo (float xx, float upper=20.f, float lower=-20.f)
	Check the argument against upper and lower boundary values prior to doing Exponential function.
float	Power (float a, float n)
	deal with positive and negative float numbers
template<typename T >
T	MaxInArray (const T *a, int n)
	Get maximum value in a numeric array with size n. More...
template<typename T >
T	MinInArray (const T *a, int n)
	Get minimum value in a numeric array with size n. More...
template<typename T >
T	Sum (int row, const T *data)
	Sum of a numeric array Get sum value of a double array with size row. More...
template<typename T >
T	Sum (int row, int *&idx, const T *data)
	Sum of a numeric array Get sum value of a double array with size row and real index idx. More...
template<typename T >
void	BasicStatistics (const T *values, int num, double **derivedvalues, T exclude=static_cast< T >(NODATA_VALUE))
	calculate basic statistics at one time_funcs More...
template<typename T >
void	BasicStatistics (const T *const *values, int num, int lyrs, double ***derivedvalues, T exclude=static_cast< T >(NODATA_VALUE))
	calculate basic statistics at one time_funcs for 2D raster data More...
float	ApprSqrt (float z)
	approximate sqrt More...
float	ApprLn (float z)
	Approximates the natural logarithm, (where the base is 'e'=2.71828)
float	pow_lookup (const float exp, const float log_base)
	lookup for pow(a, b) function More...
float	ApprPow (float a, float b)
	Approximates pow(a, b) based on the work of Harrison Ainsworth. More...

Detailed Description

Basic mathematics related functions.

Function Documentation

ApprPow()

float ccgl::utils_math::ApprPow	(	float	a,
		float	b
	)

Approximates pow(a, b) based on the work of Harrison Ainsworth.

Refers to http://www.hxa.name/articles/content/fast-pow-adjustable_hxa7241_2007.html Copyright (c) 2007, Harrison Ainsworth / HXA7241.

ApprSqrt()

float ccgl::utils_math::ApprSqrt

(

float

z

)

approximate sqrt

This uses a method to approximate sqrt which only applies to IEEE 754 floating point numbers, described in [1]. The optimized magic constant is from Chris Lomont[2]

References: 1: http://en.wikipedia.org/wiki/Fast_inverse_square_root 2: http://www.lomont.org/Math/Papers/2003/InvSqrt.pdf

Parameters

[in]

z

float or double value

Returns

approximation of sqrt

BasicStatistics() [1/2]

template<typename T >

void ccgl::utils_math::BasicStatistics	(	const T *const *	values,
		int	num,
		int	lyrs,
		double ***	derivedvalues,
		T	exclude = static_cast<T>(NODATA_VALUE)
	)

calculate basic statistics at one time_funcs for 2D raster data

Parameters

[in]	values	data array
[in]	num	data length
[in]	lyrs	layer number
[out]	derivedvalues	double array, value number, mean, max, min, std, range
[in]	exclude	optional, excluded value, e.g. NoDATA, the default is -9999

valid number

mean

maximum

minimum

std

range

valid number

mean

maximum

minimum

std

range

BasicStatistics() [2/2]

template<typename T >

void ccgl::utils_math::BasicStatistics	(	const T *	values,
		int	num,
		double **	derivedvalues,
		T	exclude = static_cast<T>(NODATA_VALUE)
	)

calculate basic statistics at one time_funcs

Parameters

[in]	values	data array
[in]	num	data length
[out]	derivedvalues	double array, value number, mean, max, min, std, range
[in]	exclude	optional, excluded value, e.g. NoDATA, the default is -9999

FloatEqual()

template<typename T1 , typename T2 >

bool ccgl::utils_math::FloatEqual	(	T1	v1,
		T2	v2
	)

Whether v1 is equal to v2.

Parameters

[in]	v1	Numeric value of data type 1
[in]	v2	Numeric value of data type 2

Returns

true or false

MaxInArray()

template<typename T >

T ccgl::utils_math::MaxInArray	(	const T *	a,
		int	n
	)

Get maximum value in a numeric array with size n.

Parameters

[in]

a,n

Returns

max value

MinInArray()

template<typename T >

T ccgl::utils_math::MinInArray	(	const T *	a,
		int	n
	)

Get minimum value in a numeric array with size n.

Parameters

[in]

a,n

Returns

min value

pow_lookup()

float ccgl::utils_math::pow_lookup	(	const float	exp,
		const float	log_base
	)

lookup for pow(a, b) function

Parameters

[in]	exp	power to raise radix to (exponent), i.e., b in pow(a, b)
[in]	log_base	one over log, to required radix, of two (ln(base))

Sum() [1/2]

template<typename T >

T ccgl::utils_math::Sum	(	int	row,
		const T *	data
	)

Sum of a numeric array Get sum value of a double array with size row.

Parameters

[in]	row
[in]	data

Returns

sum

Sum() [2/2]

template<typename T >

T ccgl::utils_math::Sum	(	int	row,
		int *&	idx,
		const T *	data
	)

Sum of a numeric array Get sum value of a double array with size row and real index idx.

Parameters

[in]	row
[in]	idx
[in]	data

Returns

sum