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fftw_plan fftw_plan_dft_1d(int n, d@0: fftw_complex *in, fftw_complex *out, d@0: int sign, unsigned flags); d@0: fftw_plan fftw_plan_dft_2d(int n0, int n1, d@0: fftw_complex *in, fftw_complex *out, d@0: int sign, unsigned flags); d@0: fftw_plan fftw_plan_dft_3d(int n0, int n1, int n2, d@0: fftw_complex *in, fftw_complex *out, d@0: int sign, unsigned flags); d@0: fftw_plan fftw_plan_dft(int rank, const int *n, d@0: fftw_complex *in, fftw_complex *out, d@0: int sign, unsigned flags); d@0:d@0:
d@0: Plan a complex input/output discrete Fourier transform (DFT) in zero or
d@0: more dimensions, returning an fftw_plan (see Using Plans).
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Once you have created a plan for a certain transform type and d@0: parameters, then creating another plan of the same type and parameters, d@0: but for different arrays, is fast and shares constant data with the d@0: first plan (if it still exists). d@0: d@0:
The planner returns NULL if the plan cannot be created. A
d@0: non-NULL plan is always returned by the basic interface unless
d@0: you are using a customized FFTW configuration supporting a restricted
d@0: set of transforms.
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rank is the dimensionality of the transform (it should be the
d@0: size of the array *n), and can be any non-negative integer. The
d@0: `_1d', `_2d', and `_3d' planners correspond to a
d@0: rank of 1, 2, and 3, respectively. A
d@0: rank of zero is equivalent to a transform of size 1, i.e. a copy
d@0: of one number from input to output.
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d@0: n, or n0/n1/n2, or n[rank],
d@0: respectively, gives the size of the transform dimensions. They can be
d@0: any positive integer.
d@0:
d@0: n0 x n1; or n0 x n1 x n2; or
d@0: n[0] x n[1] x ... x n[rank-1].
d@0: See Multi-dimensional Array Format.
d@0: performance even for prime sizes). It is possible to customize FFTW d@0: for different array sizes; see Installation and Customization. d@0: Transforms whose sizes are powers of 2 are especially fast. d@0:
in and out point to the input and output arrays of the
d@0: transform, which may be the same (yielding an in-place transform).
d@0: These arrays are overwritten during planning, unless
d@0: FFTW_ESTIMATE is used in the flags. (The arrays need not be
d@0: initialized, but they must be allocated.)
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d@0: If in == out, the transform is in-place and the input
d@0: array is overwritten. If in != out, the two arrays must
d@0: not overlap (but FFTW does not check for this condition).
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sign is the sign of the exponent in the formula that defines the
d@0: Fourier transform. It can be -1 (= FFTW_FORWARD) or
d@0: +1 (= FFTW_BACKWARD).
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d@0: flags is a bitwise OR (`|') of zero or more planner flags,
d@0: as defined in Planner Flags.
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d@0: FFTW computes an unnormalized transform: computing a forward followed by d@0: a backward transform (or vice versa) will result in the original data d@0: multiplied by the size of the transform (the product of the dimensions). d@0: For more information, see What FFTW Really Computes. d@0: d@0: d@0: d@0: