Isis::FourierTransform Class Reference

Fourier Transform class. More...

#include <FourierTransform.h>

Collaboration diagram for Isis::FourierTransform:

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.

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

Constructor & Destructor Documentation

FourierTransform()

Isis::FourierTransform::FourierTransform

(

)

Constructs the FourierTransform object.

~FourierTransform()

Isis::FourierTransform::~FourierTransform

(

)

Destroys the FourierTransform object.

Member Function Documentation

BitReverse()

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

Referenced by Transform().

Inverse()

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().

IsPowerOfTwo()

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().

lg()

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().

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().

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 Inverse().

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

• /Users/astamile/ISIS3/isis/src/base/objs/FourierTransform/FourierTransform.h
• /Users/astamile/ISIS3/isis/src/base/objs/FourierTransform/FourierTransform.cpp