sptranf.f File Reference

Perform a scalar spherical transform. More...

Go to the source code of this file.

Functions/Subroutines
subroutine	sptranf (IROMB, MAXWV, IDRT, IMAX, JMAX, KMAX, IP, IS, JN, JS, KW, KG, JB, JE, JC, WAVE, GRIDN, GRIDS, IDIR)
	This subprogram performs a spherical transform between spectral coefficients of scalar quantities and fields on a global cylindrical grid. More...

Detailed Description

Perform a scalar spherical transform.

Program History Log

Date	Programmer	Comments
96-02-29	Iredell	Initial.
1998-12-15	Iredell	Generic fft used, openmp directives inserted
2013-01-16	Iredell, Mirvis	Fixing afft negative sharing effect

Author

Iredell

Date

96-02-29

Definition in file sptranf.f.

Function/Subroutine Documentation

sptranf()

subroutine sptranf	(		IROMB,
			MAXWV,
			IDRT,
			IMAX,
			JMAX,
			KMAX,
			IP,
			IS,
			JN,
			JS,
			KW,
			KG,
			JB,
			JE,
			JC,
		real, dimension(*)	WAVE,
		real, dimension(*)	GRIDN,
		real, dimension(*)	GRIDS,
			IDIR
	)

This subprogram performs a spherical transform between spectral coefficients of scalar quantities and fields on a global cylindrical grid.

The wave-space can be either triangular or rhomboidal. The grid-space can be either an equally-spaced grid (with or without pole points) or a Gaussian grid.

The wave and grid fields may have general indexing, but each wave field is in sequential 'ibm order', i.e. with zonal wavenumber as the slower index.

Transforms are done in latitude pairs for efficiency; thus grid arrays for each hemisphere must be passed.

If so requested, just a subset of the latitude pairs may be transformed in each invocation of the subprogram. The transforms are all multiprocessed over latitude except the transform from fourier to spectral is multiprocessed over zonal wavenumber to ensure reproducibility.

Transform several fields at a time to improve vectorization. Subprogram can be called from a multiprocessing environment.

Minimum grid dimensions for unaliased transforms to spectral:

DIMENSION	LINEAR	QUADRATIC
IMAX	2*MAXWV+2	3*MAXWV/2*2+2
JMAX (IDRT=4,IROMB=0)	1*MAXWV+1	3*MAXWV/2+1
JMAX (IDRT=4,IROMB=1)	2*MAXWV+1	5*MAXWV/2+1
JMAX (IDRT=0,IROMB=0)	2*MAXWV+3	3*MAXWV/2*2+3
JMAX (IDRT=0,IROMB=1)	4*MAXWV+3	5*MAXWV/2*2+3
JMAX (IDRT=256,IROMB=0)	2*MAXWV+1	3*MAXWV/2*2+1
JMAX (IDRT=256,IROMB=1)	4*MAXWV+1	5*MAXWV/2*2+1

Parameters

	IROMB	spectral domain shape (0 for triangular, 1 for rhomboidal)
	MAXWV	spectral truncation
	IDRT	grid identifier IDRT=4 for Gaussian grid, IDRT=0 for equally-spaced grid including poles IDRT=256 for equally-spaced grid excluding poles
	IMAX	even number of longitudes.
	JMAX	number of latitudes.
	KMAX	number of fields to transform.
	IP	longitude index for the prime meridian
	IS	skip number between longitudes
	JN	skip number between n.h. latitudes from north
	JS	skip number between s.h. latitudes from south
	KW	skip number between wave fields
	KG	skip number between grid fields
	JB	latitude index (from pole) to begin transform
	JE	latitude index (from pole) to end transform
	JC	number of cpus over which to multiprocess
[out]	WAVE	wave fields if IDIR>0
[out]	GRIDN	n.h. grid fields (starting at JB) if IDIR<0
[out]	GRIDS	s.h. grid fields (starting at JB) if IDIR<0
	IDIR	transform flag (IDIR>0 for wave to grid, IDIR<0 for grid to wave)

Author

Iredell

Date

96-02-29

Definition at line 74 of file sptranf.f.

References sptranf0(), and sptranf1().

Referenced by sptez(), sptezm(), and sptran().