# ezffti.f

          SUBROUTINE EZFFTI (N, WSAVE)
    C***BEGIN PROLOGUE  EZFFTI
    C***PURPOSE  Initialize a work array for EZFFTF and EZFFTB.
    C***LIBRARY   SLATEC (FFTPACK)
    C***CATEGORY  J1A1
    C***TYPE      SINGLE PRECISION (EZFFTI-S)
    C***KEYWORDS  FFTPACK, FOURIER TRANSFORM
    C***AUTHOR  Swarztrauber, P. N., (NCAR)
    C***DESCRIPTION
    C
    C  Subroutine EZFFTI initializes the work array WSAVE which is used in
    C  both EZFFTF and EZFFTB.  The prime factorization of N together with
    C  a tabulation of the trigonometric functions are computed and
    C  stored in WSAVE.
    C
    C  Input Parameter
    C
    C  N       the length of the sequence to be transformed.
    C
    C  Output Parameter
    C
    C  WSAVE   a work array which must be dimensioned at least 3*N+15.
    C          The same work array can be used for both EZFFTF and EZFFTB
    C          as long as N remains unchanged.  Different WSAVE arrays
    C          are required for different values of N.
    C
    C***REFERENCES  P. N. Swarztrauber, Vectorizing the FFTs, in Parallel
    C                 Computations (G. Rodrigue, ed.), Academic Press,
    C                 1982, pp. 51-83.
    C***ROUTINES CALLED  EZFFT1
    C***REVISION HISTORY  (YYMMDD)
    C   790601  DATE WRITTEN
    C   830401  Modified to use SLATEC library source file format.
    C   860115  Modified by Ron Boisvert to adhere to Fortran 77 by
    C           changing dummy array size declarations (1) to (*).
    C   861211  REVISION DATE from Version 3.2
    C   881128  Modified by Dick Valent to meet prologue standards.
    C   891214  Prologue converted to Version 4.0 format.  (BAB)
    C   920501  Reformatted the REFERENCES section.  (WRB)
    C***END PROLOGUE  EZFFTI