NCEPLIBS-sp  2.3.3
Functions/Subroutines
splat.F File Reference

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Functions/Subroutines

subroutine splat (IDRT, JMAX, SLAT, WLAT)
 Computes cosines of colatitude and gaussian weights for one of the following specific global sets of latitudes. More...
 

Detailed Description

Compute latitude functions

Author
IREDELL
Date
96-02-20

Definition in file splat.F.

Function/Subroutine Documentation

◆ splat()

subroutine splat (   IDRT,
  JMAX,
real, dimension(jmax)  SLAT,
real, dimension(jmax)  WLAT 
)

Computes cosines of colatitude and gaussian weights for one of the following specific global sets of latitudes.

  • Gaussian latitudes (IDRT=4)
  • Equally-spaced latitudes including poles (IDRT=0)
  • Equally-spaced latitudes excluding poles (IDRT=256) The gaussian latitudes are located at the zeroes of the legendre polynomial of the given order. these latitudes are efficient for reversible transforms from spectral space. (About twice as many equally-spaced latitudes are needed.) The weights for the equally-spaced latitudes are based on Ellsaesser (JAM,1966). (No weight is given the pole point.) Note that when analyzing grid to spectral in latitude pairs, if an equator point exists, its weight should be halved. This version invokes the ibm essl matrix solver.

PROGRAM HISTORY LOG:

  • 96-02-20 IREDELL
  • 97-10-20 IREDELL ADJUST PRECISION
  • 98-06-11 IREDELL GENERALIZE PRECISION USING FORTRAN 90 INTRINSIC
  • 1998-12-03 IREDELL GENERALIZE PRECISION FURTHER
  • 1998-12-03 IREDELL USES AIX ESSL BLAS CALLS
  • 2009-12-27 DSTARK updated to switch between ESSL calls on an AIX platform, and Numerical Recipies calls elsewise.
  • 2010-12-30 SLOVACEK update alignment so preprocessor does not cause compilation failure
  • 2012-09-01 E.Mirvis & M.Iredell merging & debugging linux errors of _d and _8 using generic LU factorization.
  • 2012-11-05 E.Mirvis generic FFTPACK and LU lapack were removed
Parameters
IDRT- INTEGER GRID IDENTIFIER (IDRT=4 FOR GAUSSIAN GRID, IDRT=0 FOR EQUALLY-SPACED GRID INCLUDING POLES, IDRT=256 FOR EQUALLY-SPACED GRID EXCLUDING POLES)
JMAX- INTEGER NUMBER OF LATITUDES.
[out]SLAT- REAL (JMAX) SINES OF LATITUDE.
[out]WLAT- REAL (JMAX) GAUSSIAN WEIGHTS.

SUBPROGRAMS CALLED:

  • dgef() MATRIX FACTORIZATION - ESSL
  • dges() MATRIX SOLVER - ESSL
  • ludcmp() LU factorization - numerical recipies
  • lubksb() Matrix solver - numerical recipies

Definition at line 50 of file splat.F.