W3FT09

The W3FT09 routine computes 2.5 x 2.5 N. hemi. grid
           of 145 x 37 points from spectral coefficients in
           a rhomboidal 30 resolution representing a vector field.

USAGE:  CALL W3FT09(VLN,GN,PLN,EPS,FL,WORK,TRIGS,RCOS)

   Input variables:
      VLN    ARG LIST  992 COMPLEX COEFF.
      PLN    ARG LIST  992 SPACE FOR LEGENDRE POLYNOMIALS.
      EPS    ARG LIST  992 REAL SPACE FOR
                       COEFFS. USED IN COMPUTING PLN.
      FL     ARG LIST  31 COMPLEX SPACE FOR FOURIER COEFF.
      WORK   ARG LIST  144 WORK SPACE FOR SUBR. W3FT12
      TRIGS  ARG LIST  216 PRECOMPUTED TRIG FUNCS. USED
                       IN W3FT12, COMPUTED BY W3FA13
      RCOS   ARG LIST  37 RECIPROCAL COSINE LATITUDES OF
                       2.5 X 2.5 GRID MUST BE COMPUTED BEFORE
                       FIRST CALL TO W3FT11 USING SR W3FA13.
 
   Output variables:
      GN     ARG LIST  (145,37) GRID VALUES.
                       5365 POINT GRID IS TYPE 29 OR 1D O.N. 84
 
REMARKS:
        THIS SUBROUTINE WAS OPTIMIZED TO RUN IN A SMALL AMOUNT OF
        MEMORY, IT IS NOT OPTIMIZED FOR SPEED, 70 PERCENT OF THE TIME IS
        USED BY SUBROUTINE W3FA12 COMPUTING THE LEGENDRE POLYNOMIALS. SINCE
        THE LEGENDRE POLYNOMIALS ARE CONSTANT THEY NEED TO BE COMPUTED
        ONLY ONCE IN A PROGRAM. BY MOVING W3FA12 TO THE MAIN PROGRAM AND
        COMPUTING PLN AS A (32,31,37) ARRAY AND CHANGING THIS SUBROUTINE
        TO USE PLN AS A THREE DIMENSION ARRAY YOU CAN CUT THE RUNNING
        TIME 70 PERCENT.
  
 
W3lib.tar Library contains Fortran 90 decoder/encoder routines for GRIB edition 1. (Fortran90)
Date posted: 2/22/2007