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- Path: news.bu.edu!usenet
- From: Xiangyang Wang <xianwang@chem.bu.edu>
- Newsgroups: comp.lang.fortran,comp.lang.c
- Subject: Re: Efficient Column-wise FFT Routines?
- Date: Sun, 31 Mar 1996 12:19:52 -0500
- Organization: Boston University
- Message-ID: <315EBEB8.41C67EA6@chem.bu.edu>
- References: <warrenp-2603961110500001@ren.colorado.edu>
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-
- Pete Warren wrote:
- >
- > Greetings all,
- >
- > I am trying to perform large scale FFT's on complex data in a column (or
- > row) wise formats. Does anyone know of a good, proven routine for either
- > Fortran (preferred) or C ? There are routines for complex 1-D data and
- > for real column wise data but not for both.
- >
- > What I'm actually trying to do is build a code interface node for Labview
- > that performs this function efficiently.
- >
- > I would appreciate any help or pointers.
- >
- > Thank you,
- >
- > - Pete Warren
- > warrenp@colorado.edu
- The following fft subroutine is from web resourse( I am not sure where)
- , maybe it helps.
- SUBROUTINE FOUREA( N, ISI)
- C
- C THE COOLEY-TUKEY FAST FOURIER TRANSFORM IN ANSI FORTRAN
- C
- C DATA IS A ONE-DIMENSIONAL COMPLEX ARRAY WHOSE LENGTH, N, IS A
- C POWER OF TWO. ISI IS +1 FOR AN INVERSE TRANSFORM AND -1 FOR A
- C FORWARD TRANSFORM. TRANSFORM VALUES ARE RETURNED IN THE INPUT
- C ARRAY, REPLACING THE INPUT.
- C TRANSFORM(J)=SUM(DATA(I)*W**((I-1)*(J-1))), WHERE I AND J RUN
- C FROM 1 TO N AND W = EXP (ISI*2*PI*SQRT(-1)/N). PROGRAM ALSO
- C COMPUTES INVERSE TRANSFORM, FOR WHICH THE DEFINING EXPRESSION
- C IS INVTR(J)=(1/N)*SUM(DATA(I)*W**((I-1)*(J-1))).
- C RUNNING TIME IS PROPORTIONAL TO N*LOG2(N), RATHER THAN TO THE
- C CLASSICAL N**2.
- C AFTER PROGRAM BY BRENNER, JUNE 1967. THIS IS A VERY SHORT VERSION
- C OF THE FFT AND IS INTENDED MAINLY FOR DEMONSTRATION. PROGRAMS
- C ARE AVAILABLE IN THIS COLLECTION WHICH RUN FASTER AND ARE NOT
- C RESTRICTED TO POWERS OF 2 OR TO ONE-DIMENSIONAL ARRAYS.
- C SEE -- IEEE TRANS AUDIO (JUNE 1967), SPECIAL ISSUE ON FFT.
- C
- -Xiangyang
- .
-