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800 lines
26 KiB
C
800 lines
26 KiB
C
/*
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Interface for the f2c translation of fftpack as found on http://www.netlib.org/fftpack/
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FFTPACK license:
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http://www.cisl.ucar.edu/css/software/fftpack5/ftpk.html
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Copyright (c) 2004 the University Corporation for Atmospheric
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Research ("UCAR"). All rights reserved. Developed by NCAR's
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Computational and Information Systems Laboratory, UCAR,
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www.cisl.ucar.edu.
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Redistribution and use of the Software in source and binary forms,
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with or without modification, is permitted provided that the
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following conditions are met:
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- Neither the names of NCAR's Computational and Information Systems
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Laboratory, the University Corporation for Atmospheric Research,
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nor the names of its sponsors or contributors may be used to
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endorse or promote products derived from this Software without
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specific prior written permission.
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- Redistributions of source code must retain the above copyright
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notices, this list of conditions, and the disclaimer below.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions, and the disclaimer below in the
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documentation and/or other materials provided with the
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distribution.
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THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO THE WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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NONINFRINGEMENT. IN NO EVENT SHALL THE CONTRIBUTORS OR COPYRIGHT
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HOLDERS BE LIABLE FOR ANY CLAIM, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
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SOFTWARE.
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ChangeLog:
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2011/10/02: this is my first release of this file.
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*/
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#ifndef FFTPACK_H
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#define FFTPACK_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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// just define FFTPACK_DOUBLE_PRECISION if you want to build it as a double precision fft
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#ifndef FFTPACK_DOUBLE_PRECISION
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typedef float fftpack_real;
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typedef int fftpack_int;
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#else
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typedef double fftpack_real;
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typedef int fftpack_int;
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#endif
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void cffti(fftpack_int n, fftpack_real *wsave);
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void cfftf(fftpack_int n, fftpack_real *c, fftpack_real *wsave);
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void cfftb(fftpack_int n, fftpack_real *c, fftpack_real *wsave);
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void rffti(fftpack_int n, fftpack_real *wsave);
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void rfftf(fftpack_int n, fftpack_real *r, fftpack_real *wsave);
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void rfftb(fftpack_int n, fftpack_real *r, fftpack_real *wsave);
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void cosqi(fftpack_int n, fftpack_real *wsave);
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void cosqf(fftpack_int n, fftpack_real *x, fftpack_real *wsave);
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void cosqb(fftpack_int n, fftpack_real *x, fftpack_real *wsave);
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void costi(fftpack_int n, fftpack_real *wsave);
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void cost(fftpack_int n, fftpack_real *x, fftpack_real *wsave);
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void sinqi(fftpack_int n, fftpack_real *wsave);
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void sinqb(fftpack_int n, fftpack_real *x, fftpack_real *wsave);
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void sinqf(fftpack_int n, fftpack_real *x, fftpack_real *wsave);
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void sinti(fftpack_int n, fftpack_real *wsave);
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void sint(fftpack_int n, fftpack_real *x, fftpack_real *wsave);
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#ifdef __cplusplus
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}
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#endif
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#endif /* FFTPACK_H */
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/*
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FFTPACK
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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version 4 april 1985
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a package of fortran subprograms for the fast fourier
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transform of periodic and other symmetric sequences
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by
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paul n swarztrauber
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national center for atmospheric research boulder,colorado 80307
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which is sponsored by the national science foundation
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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this package consists of programs which perform fast fourier
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transforms for both complex and real periodic sequences and
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certain other symmetric sequences that are listed below.
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1. rffti initialize rfftf and rfftb
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2. rfftf forward transform of a real periodic sequence
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3. rfftb backward transform of a real coefficient array
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4. ezffti initialize ezfftf and ezfftb
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5. ezfftf a simplified real periodic forward transform
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6. ezfftb a simplified real periodic backward transform
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7. sinti initialize sint
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8. sint sine transform of a real odd sequence
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9. costi initialize cost
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10. cost cosine transform of a real even sequence
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11. sinqi initialize sinqf and sinqb
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12. sinqf forward sine transform with odd wave numbers
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13. sinqb unnormalized inverse of sinqf
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14. cosqi initialize cosqf and cosqb
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15. cosqf forward cosine transform with odd wave numbers
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16. cosqb unnormalized inverse of cosqf
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17. cffti initialize cfftf and cfftb
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18. cfftf forward transform of a complex periodic sequence
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19. cfftb unnormalized inverse of cfftf
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******************************************************************
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subroutine rffti(n,wsave)
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****************************************************************
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subroutine rffti initializes the array wsave which is used in
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both rfftf and rfftb. the prime factorization of n together with
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a tabulation of the trigonometric functions are computed and
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stored in wsave.
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input parameter
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n the length of the sequence to be transformed.
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output parameter
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wsave a work array which must be dimensioned at least 2*n+15.
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the same work array can be used for both rfftf and rfftb
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as long as n remains unchanged. different wsave arrays
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are required for different values of n. the contents of
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wsave must not be changed between calls of rfftf or rfftb.
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******************************************************************
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subroutine rfftf(n,r,wsave)
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******************************************************************
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subroutine rfftf computes the fourier coefficients of a real
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perodic sequence (fourier analysis). the transform is defined
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below at output parameter r.
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input parameters
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n the length of the array r to be transformed. the method
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is most efficient when n is a product of small primes.
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n may change so long as different work arrays are provided
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r a real array of length n which contains the sequence
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to be transformed
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wsave a work array which must be dimensioned at least 2*n+15.
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in the program that calls rfftf. the wsave array must be
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initialized by calling subroutine rffti(n,wsave) and a
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different wsave array must be used for each different
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value of n. this initialization does not have to be
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repeated so long as n remains unchanged thus subsequent
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transforms can be obtained faster than the first.
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the same wsave array can be used by rfftf and rfftb.
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output parameters
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r r(1) = the sum from i=1 to i=n of r(i)
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if n is even set l =n/2 , if n is odd set l = (n+1)/2
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then for k = 2,...,l
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r(2*k-2) = the sum from i = 1 to i = n of
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r(i)*cos((k-1)*(i-1)*2*pi/n)
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r(2*k-1) = the sum from i = 1 to i = n of
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-r(i)*sin((k-1)*(i-1)*2*pi/n)
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if n is even
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r(n) = the sum from i = 1 to i = n of
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(-1)**(i-1)*r(i)
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***** note
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this transform is unnormalized since a call of rfftf
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followed by a call of rfftb will multiply the input
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sequence by n.
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wsave contains results which must not be destroyed between
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calls of rfftf or rfftb.
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******************************************************************
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subroutine rfftb(n,r,wsave)
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******************************************************************
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subroutine rfftb computes the real perodic sequence from its
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fourier coefficients (fourier synthesis). the transform is defined
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below at output parameter r.
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input parameters
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n the length of the array r to be transformed. the method
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is most efficient when n is a product of small primes.
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n may change so long as different work arrays are provided
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r a real array of length n which contains the sequence
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to be transformed
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wsave a work array which must be dimensioned at least 2*n+15.
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in the program that calls rfftb. the wsave array must be
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initialized by calling subroutine rffti(n,wsave) and a
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different wsave array must be used for each different
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value of n. this initialization does not have to be
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repeated so long as n remains unchanged thus subsequent
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transforms can be obtained faster than the first.
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the same wsave array can be used by rfftf and rfftb.
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output parameters
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r for n even and for i = 1,...,n
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r(i) = r(1)+(-1)**(i-1)*r(n)
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plus the sum from k=2 to k=n/2 of
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2.*r(2*k-2)*cos((k-1)*(i-1)*2*pi/n)
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-2.*r(2*k-1)*sin((k-1)*(i-1)*2*pi/n)
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for n odd and for i = 1,...,n
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r(i) = r(1) plus the sum from k=2 to k=(n+1)/2 of
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2.*r(2*k-2)*cos((k-1)*(i-1)*2*pi/n)
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-2.*r(2*k-1)*sin((k-1)*(i-1)*2*pi/n)
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***** note
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this transform is unnormalized since a call of rfftf
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followed by a call of rfftb will multiply the input
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sequence by n.
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wsave contains results which must not be destroyed between
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calls of rfftb or rfftf.
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******************************************************************
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subroutine sinti(n,wsave)
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******************************************************************
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subroutine sinti initializes the array wsave which is used in
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subroutine sint. the prime factorization of n together with
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a tabulation of the trigonometric functions are computed and
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stored in wsave.
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input parameter
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n the length of the sequence to be transformed. the method
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is most efficient when n+1 is a product of small primes.
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output parameter
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wsave a work array with at least int(2.5*n+15) locations.
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different wsave arrays are required for different values
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of n. the contents of wsave must not be changed between
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calls of sint.
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******************************************************************
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subroutine sint(n,x,wsave)
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******************************************************************
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subroutine sint computes the discrete fourier sine transform
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of an odd sequence x(i). the transform is defined below at
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output parameter x.
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sint is the unnormalized inverse of itself since a call of sint
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followed by another call of sint will multiply the input sequence
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x by 2*(n+1).
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the array wsave which is used by subroutine sint must be
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initialized by calling subroutine sinti(n,wsave).
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input parameters
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n the length of the sequence to be transformed. the method
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is most efficient when n+1 is the product of small primes.
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x an array which contains the sequence to be transformed
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wsave a work array with dimension at least int(2.5*n+15)
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in the program that calls sint. the wsave array must be
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initialized by calling subroutine sinti(n,wsave) and a
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different wsave array must be used for each different
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value of n. this initialization does not have to be
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repeated so long as n remains unchanged thus subsequent
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transforms can be obtained faster than the first.
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output parameters
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x for i=1,...,n
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x(i)= the sum from k=1 to k=n
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2*x(k)*sin(k*i*pi/(n+1))
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a call of sint followed by another call of
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sint will multiply the sequence x by 2*(n+1).
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hence sint is the unnormalized inverse
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of itself.
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wsave contains initialization calculations which must not be
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destroyed between calls of sint.
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******************************************************************
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subroutine costi(n,wsave)
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******************************************************************
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subroutine costi initializes the array wsave which is used in
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subroutine cost. the prime factorization of n together with
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a tabulation of the trigonometric functions are computed and
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stored in wsave.
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input parameter
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n the length of the sequence to be transformed. the method
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is most efficient when n-1 is a product of small primes.
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output parameter
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wsave a work array which must be dimensioned at least 3*n+15.
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different wsave arrays are required for different values
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of n. the contents of wsave must not be changed between
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calls of cost.
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******************************************************************
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subroutine cost(n,x,wsave)
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******************************************************************
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subroutine cost computes the discrete fourier cosine transform
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of an even sequence x(i). the transform is defined below at output
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parameter x.
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cost is the unnormalized inverse of itself since a call of cost
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followed by another call of cost will multiply the input sequence
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x by 2*(n-1). the transform is defined below at output parameter x
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the array wsave which is used by subroutine cost must be
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initialized by calling subroutine costi(n,wsave).
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input parameters
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n the length of the sequence x. n must be greater than 1.
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the method is most efficient when n-1 is a product of
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small primes.
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x an array which contains the sequence to be transformed
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wsave a work array which must be dimensioned at least 3*n+15
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in the program that calls cost. the wsave array must be
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initialized by calling subroutine costi(n,wsave) and a
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different wsave array must be used for each different
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value of n. this initialization does not have to be
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repeated so long as n remains unchanged thus subsequent
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transforms can be obtained faster than the first.
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output parameters
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x for i=1,...,n
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x(i) = x(1)+(-1)**(i-1)*x(n)
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+ the sum from k=2 to k=n-1
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2*x(k)*cos((k-1)*(i-1)*pi/(n-1))
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a call of cost followed by another call of
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cost will multiply the sequence x by 2*(n-1)
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hence cost is the unnormalized inverse
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of itself.
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wsave contains initialization calculations which must not be
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destroyed between calls of cost.
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******************************************************************
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subroutine sinqi(n,wsave)
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******************************************************************
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subroutine sinqi initializes the array wsave which is used in
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both sinqf and sinqb. the prime factorization of n together with
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a tabulation of the trigonometric functions are computed and
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stored in wsave.
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input parameter
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n the length of the sequence to be transformed. the method
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is most efficient when n is a product of small primes.
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output parameter
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wsave a work array which must be dimensioned at least 3*n+15.
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the same work array can be used for both sinqf and sinqb
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as long as n remains unchanged. different wsave arrays
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are required for different values of n. the contents of
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wsave must not be changed between calls of sinqf or sinqb.
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******************************************************************
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subroutine sinqf(n,x,wsave)
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******************************************************************
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subroutine sinqf computes the fast fourier transform of quarter
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wave data. that is , sinqf computes the coefficients in a sine
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series representation with only odd wave numbers. the transform
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is defined below at output parameter x.
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sinqb is the unnormalized inverse of sinqf since a call of sinqf
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followed by a call of sinqb will multiply the input sequence x
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by 4*n.
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the array wsave which is used by subroutine sinqf must be
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initialized by calling subroutine sinqi(n,wsave).
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input parameters
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n the length of the array x to be transformed. the method
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is most efficient when n is a product of small primes.
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x an array which contains the sequence to be transformed
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wsave a work array which must be dimensioned at least 3*n+15.
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in the program that calls sinqf. the wsave array must be
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initialized by calling subroutine sinqi(n,wsave) and a
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different wsave array must be used for each different
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value of n. this initialization does not have to be
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repeated so long as n remains unchanged thus subsequent
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transforms can be obtained faster than the first.
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output parameters
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x for i=1,...,n
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x(i) = (-1)**(i-1)*x(n)
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+ the sum from k=1 to k=n-1 of
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2*x(k)*sin((2*i-1)*k*pi/(2*n))
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a call of sinqf followed by a call of
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sinqb will multiply the sequence x by 4*n.
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therefore sinqb is the unnormalized inverse
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of sinqf.
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wsave contains initialization calculations which must not
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be destroyed between calls of sinqf or sinqb.
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******************************************************************
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subroutine sinqb(n,x,wsave)
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******************************************************************
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subroutine sinqb computes the fast fourier transform of quarter
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wave data. that is , sinqb computes a sequence from its
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representation in terms of a sine series with odd wave numbers.
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the transform is defined below at output parameter x.
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sinqf is the unnormalized inverse of sinqb since a call of sinqb
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followed by a call of sinqf will multiply the input sequence x
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by 4*n.
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the array wsave which is used by subroutine sinqb must be
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initialized by calling subroutine sinqi(n,wsave).
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input parameters
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n the length of the array x to be transformed. the method
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is most efficient when n is a product of small primes.
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x an array which contains the sequence to be transformed
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wsave a work array which must be dimensioned at least 3*n+15.
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in the program that calls sinqb. the wsave array must be
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initialized by calling subroutine sinqi(n,wsave) and a
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different wsave array must be used for each different
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value of n. this initialization does not have to be
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repeated so long as n remains unchanged thus subsequent
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transforms can be obtained faster than the first.
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output parameters
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x for i=1,...,n
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x(i)= the sum from k=1 to k=n of
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|
|
4*x(k)*sin((2k-1)*i*pi/(2*n))
|
|
|
|
a call of sinqb followed by a call of
|
|
sinqf will multiply the sequence x by 4*n.
|
|
therefore sinqf is the unnormalized inverse
|
|
of sinqb.
|
|
|
|
wsave contains initialization calculations which must not
|
|
be destroyed between calls of sinqb or sinqf.
|
|
|
|
******************************************************************
|
|
|
|
subroutine cosqi(n,wsave)
|
|
|
|
******************************************************************
|
|
|
|
subroutine cosqi initializes the array wsave which is used in
|
|
both cosqf and cosqb. the prime factorization of n together with
|
|
a tabulation of the trigonometric functions are computed and
|
|
stored in wsave.
|
|
|
|
input parameter
|
|
|
|
n the length of the array to be transformed. the method
|
|
is most efficient when n is a product of small primes.
|
|
|
|
output parameter
|
|
|
|
wsave a work array which must be dimensioned at least 3*n+15.
|
|
the same work array can be used for both cosqf and cosqb
|
|
as long as n remains unchanged. different wsave arrays
|
|
are required for different values of n. the contents of
|
|
wsave must not be changed between calls of cosqf or cosqb.
|
|
|
|
******************************************************************
|
|
|
|
subroutine cosqf(n,x,wsave)
|
|
|
|
******************************************************************
|
|
|
|
subroutine cosqf computes the fast fourier transform of quarter
|
|
wave data. that is , cosqf computes the coefficients in a cosine
|
|
series representation with only odd wave numbers. the transform
|
|
is defined below at output parameter x
|
|
|
|
cosqf is the unnormalized inverse of cosqb since a call of cosqf
|
|
followed by a call of cosqb will multiply the input sequence x
|
|
by 4*n.
|
|
|
|
the array wsave which is used by subroutine cosqf must be
|
|
initialized by calling subroutine cosqi(n,wsave).
|
|
|
|
|
|
input parameters
|
|
|
|
n the length of the array x to be transformed. the method
|
|
is most efficient when n is a product of small primes.
|
|
|
|
x an array which contains the sequence to be transformed
|
|
|
|
wsave a work array which must be dimensioned at least 3*n+15
|
|
in the program that calls cosqf. the wsave array must be
|
|
initialized by calling subroutine cosqi(n,wsave) and a
|
|
different wsave array must be used for each different
|
|
value of n. this initialization does not have to be
|
|
repeated so long as n remains unchanged thus subsequent
|
|
transforms can be obtained faster than the first.
|
|
|
|
output parameters
|
|
|
|
x for i=1,...,n
|
|
|
|
x(i) = x(1) plus the sum from k=2 to k=n of
|
|
|
|
2*x(k)*cos((2*i-1)*(k-1)*pi/(2*n))
|
|
|
|
a call of cosqf followed by a call of
|
|
cosqb will multiply the sequence x by 4*n.
|
|
therefore cosqb is the unnormalized inverse
|
|
of cosqf.
|
|
|
|
wsave contains initialization calculations which must not
|
|
be destroyed between calls of cosqf or cosqb.
|
|
|
|
******************************************************************
|
|
|
|
subroutine cosqb(n,x,wsave)
|
|
|
|
******************************************************************
|
|
|
|
subroutine cosqb computes the fast fourier transform of quarter
|
|
wave data. that is , cosqb computes a sequence from its
|
|
representation in terms of a cosine series with odd wave numbers.
|
|
the transform is defined below at output parameter x.
|
|
|
|
cosqb is the unnormalized inverse of cosqf since a call of cosqb
|
|
followed by a call of cosqf will multiply the input sequence x
|
|
by 4*n.
|
|
|
|
the array wsave which is used by subroutine cosqb must be
|
|
initialized by calling subroutine cosqi(n,wsave).
|
|
|
|
|
|
input parameters
|
|
|
|
n the length of the array x to be transformed. the method
|
|
is most efficient when n is a product of small primes.
|
|
|
|
x an array which contains the sequence to be transformed
|
|
|
|
wsave a work array that must be dimensioned at least 3*n+15
|
|
in the program that calls cosqb. the wsave array must be
|
|
initialized by calling subroutine cosqi(n,wsave) and a
|
|
different wsave array must be used for each different
|
|
value of n. this initialization does not have to be
|
|
repeated so long as n remains unchanged thus subsequent
|
|
transforms can be obtained faster than the first.
|
|
|
|
output parameters
|
|
|
|
x for i=1,...,n
|
|
|
|
x(i)= the sum from k=1 to k=n of
|
|
|
|
4*x(k)*cos((2*k-1)*(i-1)*pi/(2*n))
|
|
|
|
a call of cosqb followed by a call of
|
|
cosqf will multiply the sequence x by 4*n.
|
|
therefore cosqf is the unnormalized inverse
|
|
of cosqb.
|
|
|
|
wsave contains initialization calculations which must not
|
|
be destroyed between calls of cosqb or cosqf.
|
|
|
|
******************************************************************
|
|
|
|
subroutine cffti(n,wsave)
|
|
|
|
******************************************************************
|
|
|
|
subroutine cffti initializes the array wsave which is used in
|
|
both cfftf and cfftb. the prime factorization of n together with
|
|
a tabulation of the trigonometric functions are computed and
|
|
stored in wsave.
|
|
|
|
input parameter
|
|
|
|
n the length of the sequence to be transformed
|
|
|
|
output parameter
|
|
|
|
wsave a work array which must be dimensioned at least 4*n+15
|
|
the same work array can be used for both cfftf and cfftb
|
|
as long as n remains unchanged. different wsave arrays
|
|
are required for different values of n. the contents of
|
|
wsave must not be changed between calls of cfftf or cfftb.
|
|
|
|
******************************************************************
|
|
|
|
subroutine cfftf(n,c,wsave)
|
|
|
|
******************************************************************
|
|
|
|
subroutine cfftf computes the forward complex discrete fourier
|
|
transform (the fourier analysis). equivalently , cfftf computes
|
|
the fourier coefficients of a complex periodic sequence.
|
|
the transform is defined below at output parameter c.
|
|
|
|
the transform is not normalized. to obtain a normalized transform
|
|
the output must be divided by n. otherwise a call of cfftf
|
|
followed by a call of cfftb will multiply the sequence by n.
|
|
|
|
the array wsave which is used by subroutine cfftf must be
|
|
initialized by calling subroutine cffti(n,wsave).
|
|
|
|
input parameters
|
|
|
|
|
|
n the length of the complex sequence c. the method is
|
|
more efficient when n is the product of small primes. n
|
|
|
|
c a complex array of length n which contains the sequence
|
|
|
|
wsave a real work array which must be dimensioned at least 4n+15
|
|
in the program that calls cfftf. the wsave array must be
|
|
initialized by calling subroutine cffti(n,wsave) and a
|
|
different wsave array must be used for each different
|
|
value of n. this initialization does not have to be
|
|
repeated so long as n remains unchanged thus subsequent
|
|
transforms can be obtained faster than the first.
|
|
the same wsave array can be used by cfftf and cfftb.
|
|
|
|
output parameters
|
|
|
|
c for j=1,...,n
|
|
|
|
c(j)=the sum from k=1,...,n of
|
|
|
|
c(k)*exp(-i*(j-1)*(k-1)*2*pi/n)
|
|
|
|
where i=sqrt(-1)
|
|
|
|
wsave contains initialization calculations which must not be
|
|
destroyed between calls of subroutine cfftf or cfftb
|
|
|
|
******************************************************************
|
|
|
|
subroutine cfftb(n,c,wsave)
|
|
|
|
******************************************************************
|
|
|
|
subroutine cfftb computes the backward complex discrete fourier
|
|
transform (the fourier synthesis). equivalently , cfftb computes
|
|
a complex periodic sequence from its fourier coefficients.
|
|
the transform is defined below at output parameter c.
|
|
|
|
a call of cfftf followed by a call of cfftb will multiply the
|
|
sequence by n.
|
|
|
|
the array wsave which is used by subroutine cfftb must be
|
|
initialized by calling subroutine cffti(n,wsave).
|
|
|
|
input parameters
|
|
|
|
|
|
n the length of the complex sequence c. the method is
|
|
more efficient when n is the product of small primes.
|
|
|
|
c a complex array of length n which contains the sequence
|
|
|
|
wsave a real work array which must be dimensioned at least 4n+15
|
|
in the program that calls cfftb. the wsave array must be
|
|
initialized by calling subroutine cffti(n,wsave) and a
|
|
different wsave array must be used for each different
|
|
value of n. this initialization does not have to be
|
|
repeated so long as n remains unchanged thus subsequent
|
|
transforms can be obtained faster than the first.
|
|
the same wsave array can be used by cfftf and cfftb.
|
|
|
|
output parameters
|
|
|
|
c for j=1,...,n
|
|
|
|
c(j)=the sum from k=1,...,n of
|
|
|
|
c(k)*exp(i*(j-1)*(k-1)*2*pi/n)
|
|
|
|
where i=sqrt(-1)
|
|
|
|
wsave contains initialization calculations which must not be
|
|
destroyed between calls of subroutine cfftf or cfftb
|
|
|
|
*/
|