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48 lines
1.8 KiB
Fortran
48 lines
1.8 KiB
Fortran
*DECK SINQI
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SUBROUTINE SINQI (N, WSAVE)
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C***BEGIN PROLOGUE SINQI
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C***PURPOSE Initialize a work array for SINQF and SINQB.
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C***LIBRARY SLATEC (FFTPACK)
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C***CATEGORY J1A3
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C***TYPE SINGLE PRECISION (SINQI-S)
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C***KEYWORDS FFTPACK, FOURIER TRANSFORM
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C***AUTHOR Swarztrauber, P. N., (NCAR)
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C***DESCRIPTION
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C
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C Subroutine SINQI initializes the array WSAVE which is used in
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C both SINQF and SINQB. The prime factorization of N together with
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C a tabulation of the trigonometric functions are computed and
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C stored in WSAVE.
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C
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C Input Parameter
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C
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C N the length of the sequence to be transformed. The method
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C is most efficient when N is a product of small primes.
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C
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C Output Parameter
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C
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C WSAVE a work array which must be dimensioned at least 3*N+15.
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C The same work array can be used for both SINQF and SINQB
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C as long as N remains unchanged. Different WSAVE arrays
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C are required for different values of N. The contents of
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C WSAVE must not be changed between calls of SINQF or SINQB.
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C
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C***REFERENCES P. N. Swarztrauber, Vectorizing the FFTs, in Parallel
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C Computations (G. Rodrigue, ed.), Academic Press,
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C 1982, pp. 51-83.
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C***ROUTINES CALLED COSQI
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C***REVISION HISTORY (YYMMDD)
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C 790601 DATE WRITTEN
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C 830401 Modified to use SLATEC library source file format.
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C 860115 Modified by Ron Boisvert to adhere to Fortran 77 by
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C changing dummy array size declarations (1) to (*)
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C 861211 REVISION DATE from Version 3.2
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C 881128 Modified by Dick Valent to meet prologue standards.
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C 891214 Prologue converted to Version 4.0 format. (BAB)
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C 920501 Reformatted the REFERENCES section. (WRB)
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C***END PROLOGUE SINQI
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DIMENSION WSAVE(*)
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C***FIRST EXECUTABLE STATEMENT SINQI
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CALL COSQI (N,WSAVE)
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RETURN
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END
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