SUBROUTINE W3FT39(VLN,GN,PLN,FL,WORK,TRIGS,RCOS)
C$$$ SUBPROGRAM DOCUMENTATION BLOCK
C
C SUBPROGRAM: W3FT39 COMPUTES 2.5X2.5 N. HEMI. GRID-VECTOR
C AUTHOR: R.E.JONES ORG: W323 DATE: 84-06-27
C
C ABSTRACT: COMPUTES 2.5 X 2.5 N. HEMI. GRID OF 145 X 37 POINTS
C FROM SPECTRAL COEFFICIENTS IN A RHOMBOIDAL 30 RESOLUTION
C REPRESENTING A VECTOR FIELD.
C
C PROGRAM HISTORY LOG:
C 93-07-23 R.E.JONES NEW VERSION OF W3FT09, TAKES OUT W3FA12
C MAKES PLN 3 DIMENSIONS, PLN IS COMPUTED
C ONE TIME IN MAIN PROGRAM, TRADES MEMORY
C FOR MORE SPEED. W3FA12 USED 70% OF CPU TIME.
C
C USAGE: CALL W3FT39(VLN,GN,PLN,FL,WORK,TRIGS,RCOS)
C
C INPUT VARIABLES:
C NAMES INTERFACE DESCRIPTION OF VARIABLES AND TYPES
C ------ --------- -----------------------------------------------
C VLN ARG LIST 992 COMPLEX COEFF.
C PLN ARG LIST (32,31,37) REAL SPACE WITH LEGENDRE POLYNOMIALS
C COMPUTED BY W3FA12.
C FL ARG LIST 31 COMPLEX SPACE FOR FOURIER COEFF.
C WORK ARG LIST 144 WORK SPACE FOR SUBR. W3FT12
C TRIGS ARG LIST 216 PRECOMPUTED TRIG FUNCS. USED
C IN W3FT12, COMPUTED BY W3FA13
C RCOS ARG LIST 37 RECIPROCAL COSINE LATITUDES OF
C 2.5 X 2.5 GRID MUST BE COMPUTED BEFORE
C FIRST CALL TO W3FT11 USING SR W3FA13.
C
C OUTPUT VARIABLES:
C NAMES INTERFACE DESCRIPTION OF VARIABLES AND TYPES
C ------ --------- -----------------------------------------------
C GN ARG LIST (145,37) GRID VALUES.
C 5365 POINT GRID IS TYPE 29 OR 1D O.N. 84
C
C SUBPROGRAMS CALLED:
C NAMES LIBRARY
C ------------------------------------------------------- --------
C AIMAG CMPLX REAL SYSTEM
C W3FT12 W3LIB
C
C WARNING: W3FT09 WAS OPTIMIZED TO RUN IN A SMALL AMOUNT OF
C MEMORY, IT WAS NOT OPTIMIZED FOR SPEED, 70 PERCENT OF THE TIME WAS
C USED BY SUBROUTINE W3FA12 COMPUTING THE LEGENDRE POLYNOMIALS. SINCE
C THE LEGENDRE POLYNOMIALS ARE CONSTANT THEY NEED TO BE COMPUTED
C ONLY ONCE IN A PROGRAM. BY MOVING W3FA12 TO THE MAIN PROGRAM AND
C COMPUTING PLN AS A (32,31,37) ARRAY AND CHANGING THIS SUBROUTINE
C TO USE PLN AS A THREE DIMENSION ARRAY THE RUNNING TIME WAS CUT
C 70 PERCENT. ADD FOLLOWING CODE TO MAIN PROGRAM TO COMPUTE EPS, PLN,
C TRIGS, AND RCOS ONE TIME IN PROGRAM.
C
C DOUBLE PRECISION EPS(992)
C DOUBLE PRECISION COLRA
C
C REAL PLN( 32, 31, 37 )
C REAL RCOS(37)
C REAL TRIGS(216)
C
C DATA PI /3.14159265/
C
C DRAD = 2.5 * PI / 180.0
C CALL W3FA11(EPS,30)
C CALL W3FA13(TRIGS,RCOS)
C DO LAT = 1,37
C COLRA = (LAT - 1) * DRAD
C CALL W3FA12 (PLN(1,1,LAT), COLRA, 30, EPS)
C END DO
C
C ATTRIBUTES:
C LANGUAGE: CRAY CFT77 FORTRAN
C MACHINE: CRAY Y-MP8/864, CRAY Y-MP EL2/128
C
C$$$
C
COMPLEX FL( 31 )
COMPLEX VLN( 32 , 31 )
C
REAL GN(145,37)
REAL PLN( 32, 31, 37 )
REAL RCOS(37)
REAL TRIGS(216)
REAL WORK(144)
C
SAVE
C
DO 400 LAT = 2,37
LATN = 38 - LAT
C
DO 100 L = 1, 31
FL(L) = (0.,0.)
100 CONTINUE
C
DO 300 L = 1, 31
C
DO 200 I = 1, 32
FL(L) = FL(L) + CMPLX(PLN(I,L,LAT) * REAL(VLN(I,L)),
& PLN(I,L,LAT) * AIMAG(VLN(I,L)) )
200 CONTINUE
C
FL(L)=CMPLX(REAL(FL(L))*RCOS(LAT),AIMAG(FL(L))*RCOS(LAT))
300 CONTINUE
C
CALL W3FT12(FL,WORK,GN(1,LATN),TRIGS)
C
400 CONTINUE
C
C*** POLE ROW=CLOSEST LATITUDE ROW
C
DO 500 I = 1,145
GN(I,37) = GN(I,36)
500 CONTINUE
C
RETURN
END