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% @(#)fft_inve.hlq 19.1 (ESO-IPG) 02/25/03 14:03:20
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%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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%.COPYRIGHT (c) 1990 European Southern Observatory
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%.KEYWORDS MIDAS, help files, FFT/INVERSE
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%.PURPOSE On-line help file for the command: FFT/INVERSE
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%.VERSION 1.0 03-APR-1990 : Creation, KB
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%.VERSION 1.1 26-OCT-1992 : Upgrade, KB
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%----------------------------------------------------------------
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FFT/INVERSE 26-OCT-1992 KB
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FFT/INVERSE inr ini outr outi
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make inverse discrete Fourier transform
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Compute the inverse discrete Fourier transform of real or complex
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Transformation, filter.
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FFT/INVERSE inr ini outr outi
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inr = frame containing the real part of input frame;
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defaulted to `fftr.bdf'
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ini = frame containing the imaginary part of input frame,
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if input frame is only real, omit `ini' or set it to `?',
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if you enter values for any of the following parameters;
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defaulted to `ffti.bdf'
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outr = frame for real part of result transform;
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defaulted to `zztr.bdf'
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outi = frame for imaginary part of result transform;
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defaulted to `zzti.bdf'
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FFT/IMAGE, FFT/POWER, FFT/FINVERSE, CREATE/FILTER
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All internal calculations are done in double precision and
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only the final result frames are truncated to single precision.
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If the number of pixels in an axis of the input frame is not a power
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of 2, the input frame is expanded to the next higher power of 2.
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The result frames will have the original no. of pixels but the
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result frames with expanded size are also kept with names
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`exp_fftr.bdf' and `exp_ffti.bdf'.
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If the input frames are expanded frames from a previous FFT/IMAGE
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with input files which had dimensions not a power of 2, the frames
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`orig_r.bdf' and `orig_i.bdf' with the original size will be
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extracted from the results as well.
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This command corresponds to a previous FFT/IMAGE or FFT/POWER
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command, not a FFT/FREQUENCY command!
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Do inverse FFT for image with real part in frame `f1.bdf' and
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imaginary part in `f2.bdf', store results in frame `zztr.bdf'
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Do inverse FFT for image with real part in frame `fftr.bdf' and
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imaginary part in `ffti.bdf', store results in frame `zztr.bdf'
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Does not work for 3-dim frames.