coco
119 lines
4.0 KiB
C++
119 lines
4.0 KiB
C++
// Copyright (C) 2013 Davis E. King (davis@dlib.net)
|
|
// License: Boost Software License See LICENSE.txt for the full license.
|
|
#undef DLIB_FFt_ABSTRACT_Hh_
|
|
#ifdef DLIB_FFt_ABSTRACT_Hh_
|
|
|
|
#include "matrix_abstract.h"
|
|
#include "../algs.h"
|
|
|
|
namespace dlib
|
|
{
|
|
|
|
// ----------------------------------------------------------------------------------------
|
|
|
|
bool is_power_of_two (
|
|
const unsigned long& value
|
|
);
|
|
/*!
|
|
ensures
|
|
- returns true if value contains a power of two and false otherwise. As a
|
|
special case, we also consider 0 to be a power of two.
|
|
!*/
|
|
|
|
// ----------------------------------------------------------------------------------------
|
|
|
|
template <typename EXP>
|
|
typename EXP::matrix_type fft (
|
|
const matrix_exp<EXP>& data
|
|
);
|
|
/*!
|
|
requires
|
|
- data contains elements of type std::complex<> that itself contains double, float, or long double.
|
|
- is_power_of_two(data.nr()) == true
|
|
- is_power_of_two(data.nc()) == true
|
|
ensures
|
|
- Computes the 1 or 2 dimensional discrete Fourier transform of the given data
|
|
matrix and returns it. In particular, we return a matrix D such that:
|
|
- D.nr() == data.nr()
|
|
- D.nc() == data.nc()
|
|
- D(0,0) == the DC term of the Fourier transform.
|
|
- starting with D(0,0), D contains progressively higher frequency components
|
|
of the input data.
|
|
- ifft(D) == D
|
|
!*/
|
|
|
|
// ----------------------------------------------------------------------------------------
|
|
|
|
template <typename EXP>
|
|
typename EXP::matrix_type ifft (
|
|
const matrix_exp<EXP>& data
|
|
);
|
|
/*!
|
|
requires
|
|
- data contains elements of type std::complex<> that itself contains double, float, or long double.
|
|
- is_power_of_two(data.nr()) == true
|
|
- is_power_of_two(data.nc()) == true
|
|
ensures
|
|
- Computes the 1 or 2 dimensional inverse discrete Fourier transform of the
|
|
given data vector and returns it. In particular, we return a matrix D such
|
|
that:
|
|
- D.nr() == data.nr()
|
|
- D.nc() == data.nc()
|
|
- fft(D) == data
|
|
!*/
|
|
|
|
// ----------------------------------------------------------------------------------------
|
|
|
|
template <
|
|
typename T,
|
|
long NR,
|
|
long NC,
|
|
typename MM,
|
|
typename L
|
|
>
|
|
void fft_inplace (
|
|
matrix<std::complex<T>,NR,NC,MM,L>& data
|
|
);
|
|
/*!
|
|
requires
|
|
- data contains elements of type std::complex<> that itself contains double, float, or long double.
|
|
- is_power_of_two(data.nr()) == true
|
|
- is_power_of_two(data.nc()) == true
|
|
ensures
|
|
- This function is identical to fft() except that it does the FFT in-place.
|
|
That is, after this function executes we will have:
|
|
- #data == fft(data)
|
|
!*/
|
|
|
|
// ----------------------------------------------------------------------------------------
|
|
|
|
template <
|
|
typename T,
|
|
long NR,
|
|
long NC,
|
|
typename MM,
|
|
typename L
|
|
>
|
|
void ifft_inplace (
|
|
matrix<std::complex<T>,NR,NC,MM,L>& data
|
|
);
|
|
/*!
|
|
requires
|
|
- data contains elements of type std::complex<> that itself contains double, float, or long double.
|
|
- is_power_of_two(data.nr()) == true
|
|
- is_power_of_two(data.nc()) == true
|
|
ensures
|
|
- This function is identical to ifft() except that it does the inverse FFT
|
|
in-place. That is, after this function executes we will have:
|
|
- #data == ifft(data)*data.size()
|
|
- Note that the output needs to be divided by data.size() to complete the
|
|
inverse transformation.
|
|
!*/
|
|
|
|
// ----------------------------------------------------------------------------------------
|
|
|
|
}
|
|
|
|
#endif // DLIB_FFt_ABSTRACT_Hh_
|
|
|