Isis::FourierTransform Class Reference
[Math, Statistics]

Fourier Transform class. More...

#include <FourierTransform.h>

List of all members.

Public Member Functions
	FourierTransform ()
	Constructs the FourierTransform object.
	~FourierTransform ()
	Destroys the FourierTransform object.
std::vector< std::complex < double > >	Transform (std::vector< std::complex< double > > input)
	Applies the Fourier transform on the input data and returns the result.
std::vector< std::complex < double > >	Inverse (std::vector< std::complex< double > > input)
	Applies the inverse Fourier transform on the input data and returns the result.
bool	IsPowerOfTwo (int n)
	Checks to see if the input integer is a power of two.
int	lg (int n)
	This function returns the floor of log2(n).
int	BitReverse (int n, int x)
	Reverses the binary representation of the input integer in the number of bits specified.
int	NextPowerOfTwo (int n)
	This function returns the next power of two greater than or equal to n.

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Detailed Description

Fourier Transform class.

This class is used to apply a Fourier transform to a vector of complex data as well as the inverse Fourier transform. Applying the Fourier transform on data in the spatial domain will convert it to data in the Fourier (or frequency) domain. The inverse transform takes data from the frequency domain to the spatial.

If you would like to see FourierTransform being used in implementation, see fft.cpp or ifft.cpp.

Author:

2005-11-28 Jacob Danton

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Constructor & Destructor Documentation

Isis::FourierTransform::FourierTransform

(

)

Constructs the FourierTransform object.

Isis::FourierTransform::~FourierTransform

(

)

Destroys the FourierTransform object.

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Member Function Documentation

int Isis::FourierTransform::BitReverse	(	int	n,
		int	x
	)

Reverses the binary representation of the input integer in the number of bits specified.

bitReverse(n,x) = n/2*(2^-a1 + 2^-a2 + ... + 2^-ak) where x = 2^a1 + 2^a2 + ... + 2^ak

Parameters:

	n	The number of bits
	x	The input integer

Returns:

int - The reverse of the binary representation of the input integer

References a.

Referenced by Transform().

std::vector< std::complex< double > > Isis::FourierTransform::Inverse

(

std::vector< std::complex< double > >

input

)

Applies the inverse Fourier transform on the input data and returns the result.

Parameters:

input

The data to be transformed.

Returns:

vector

References Transform().

bool Isis::FourierTransform::IsPowerOfTwo

(

int

n

)

Checks to see if the input integer is a power of two.

Parameters:

n

The input integer

Returns:

bool - Returns true if the input is a power of two and false if it is not

Referenced by NextPowerOfTwo().

int Isis::FourierTransform::lg

(

int

n

)

This function returns the floor of log2(n).

Parameters:

n

The input integer

Returns:

int - the floor of log2(n)

Referenced by NextPowerOfTwo().

int Isis::FourierTransform::NextPowerOfTwo

(

int

n

)

This function returns the next power of two greater than or equal to n.

If n is a power of two, it returns n.

Parameters:

n

The number of bits

Returns:

int - the next power of two greater than or equal to n

References IsPowerOfTwo(), and lg().

Referenced by Isis::ForstnerOperator::Interest(), and Transform().

std::vector< std::complex< double > > Isis::FourierTransform::Transform

(

std::vector< std::complex< double > >

input

)

Applies the Fourier transform on the input data and returns the result.

Parameters:

input

The data to be transformed.

Returns:

vector

References BitReverse(), NextPowerOfTwo(), and Isis::PI().

Referenced by Isis::ForstnerOperator::Interest(), and Inverse().

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The documentation for this class was generated from the following files:

• src/base/objs/FourierTransform/FourierTransform.h
• src/base/objs/FourierTransform/FourierTransform.cpp