W3FT41

The W3FT41 routine computes 2.5 x 2.5 S. HEMI. grid of
           145 x 37 points from spectral coefficients in a
           Rhomboidal 30 resolution representing a vector field.

USAGE:  CALL W3FT41(VLN,GN,PLN,FL,WORK,TRIGS,RCOS)

   Input variables:
      VLN        992 COMPLEX COEFF.
      PLN        (32,31,37) REAL SPACE WITH LEGENDRE POLYNOMIALS
                 COMPUTED BY W3FA12.
      FL         31 COMPLEX SPACE FOR FOURIER COEFF.
      WORK       144 REAL WORK SPACE FOR SUBR. W3FT12
      TRIGS      216 PRECOMPUTED TRIG FUNCS. USED
                 IN W3FT12, COMPUTED BY W3FA13
      RCOS       37 RECIPROCAL COSINE LATITUDES OF
                 2.5 X 2.5 GRID MUST BE COMPUTED BEFORE
                 FIRST CALL TO W3FT11 USING SUBR. W3FA13.
 
   Output variables:
      GN         (145,37) GRID VALUES.
                 5365 POINT GRID IS TYPE 30 OR 1E HEX O.N. 84
 
REMARKS:
     W3FT11 WAS OPTIMIZED TO RUN IN A SMALL AMOUNT OF
     MEMORY, IT WAS NOT OPTIMIZED FOR SPEED, 70 PERCENT OF THE TIME WAS
     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 THE RUNNING TIME WAS CUT
     70 PERCENT. ADD FOLLOWING CODE TO MAIN PROGRAM TO COMPUTE EPS, PLN,
     TRIGS, AND RCOS ONE TIME IN PROGRAM.

 


  
W3lib.tar
  
Library contains Fortran 90 decoder/encoder
   routines for GRIB edition 1. (Fortran90) 

   Date posted: 2/22/2007