C
C                * * * * * * * * * * * * * * * * * * *
C                *                                   *
C                * SUBROUTINE VSCOSI(N,C1,C2,WSAVE)  *
C                *                                   *
C                * * * * * * * * * * * * * * * * * * *
C
C
C                           * * * * * * * *
C                           *   PURPOSE   *
C                           * * * * * * * *
C
C
C     A SUBROUTINE THAT COMPUTES INTERMEDIATE VALUES REQUIRED FOR THE
C     CALCULATION OF STAGGERED GRID COSINE AND SINE TRANSFORMS AND FOR
C     A REAL PERIODIC FAST FOURIER TRANSFORM.
C
C     NOTE:  SUBROUTINE VSCOSI OR VSSINI MUST BE CALLED BEFORE ANY OF
C     THE SUBROUTINES VSCOSF, VSCOSB, VSSINF, OR VSSINB ARE CALLED, BUT
C     IT NEED BE CALLED ONLY ONCE FOR ANY GIVEN VALUE OF N.
C
C
C                    * * * * * * * * * * * * * * *
C                    *   PARAMETER DESCRIPTION   *
C                    * * * * * * * * * * * * * * *
C
C
C     INPUT PARAMETER
C
C     N      THE LENGTH OF THE STAGGERED GRID COSINE OR SINE TRANSFORM
C            TO BE COMPUTED.
C
C
C     OUTPUT PARAMETERS
C
C     C1,C2  TWO REAL ONE-DIMENSIONAL ARRAYS OF LENGTH M THAT CONTAIN
C            INTERMEDIATE TRIGONOMETRIC VALUES USED IN THE STAGGERED
C            GRID TRANSFORMS.
C
C     WSAVE  A REAL ONE-DIMENSIONAL ARRAY OF LENGTH M+15 THAT CONTAINS
C            INTERMEDIATE VALUES CREATED BY THE SUBROUTINE VRFFTI FOR
C            USE IN THE COMPUTATION OF A REAL PERIODIC FAST FOURIER
C            TRANSFORM.
C
C     NOTE:  THE QUANTITIES IN THE ARRAYS C1, C2, AND WSAVE MUST NOT BE
C            DESTROYED BETWEEN SUCCESSIVE CALLS TO THE STAGGERED GRID
C            TRANSFORM ROUTINES.
C
C
C
C              * * * * * * * * * * * * * * * * * * * * *
C              *                                       *
C              *         PROGRAM SPECIFICATIONS        *
C              *                                       *
C              * * * * * * * * * * * * * * * * * * * * *
C
C
C
C     DIMENSION OF    F(L,M,N), FT(L*M*N), C1(M), C2(M), C3(M), C4(M),
C     ARGUMENTS       WSAVE(N+15)
C
C     LATEST          AUGUST 1, 1985
C     REVISION
C
C     SUBPROGRAMS     VSRFTI, VSCOSI, VSCSQI, VSRFTF, VSRFTB, VSCOSF,
C     REQUIRED        VSCOSB, VSCOSQ, VSSINF, VSSINB, VSSINQ, PIMACH,
C                     VRFFTPK (PACKAGE)
C
C     SPECIAL         NONE
C     CONDITIONS
C
C     COMMON          NONE
C     BLOCKS
C
C     I/O             NONE
C
C     PRECISION       SINGLE
C
C     SPECIALIST      ROLAND SWEET
C
C     LANGUAGE        FORTRAN
C
C     HISTORY         WRITTEN BY LINDA LINDGREN AND ROLAND SWEET AT THE
C                     NATIONAL BUREAU OF STANDARDS (BOULDER).
C
C     ALGORITHM       SEE "FAST FOURIER TRANSFORMS ON A STAGGERED GRID"
C                     BY ROLAND A. SWEET (TO APPEAR)
C
C     PORTABILITY     AMERICAN NATIONAL STANDARDS INSTITUTE FORTRAN 77.
C                     THE ONLY MACHINE DEPENDENT CONSTANT IS LOCATED IN
C                     THE FUNCTION PIMACH.
C
C     REQUIRED        COS,SIN
C     RESIDENT
C     ROUTINES
C