spgradx.f File Reference

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Functions/Subroutines
subroutine	spgradx (M, INCW, KMAX, MP, CLAT, W, WX)
	THIS SUBPROGRAM COMPUTES THE X-GRADIENT OF FIELDS IN COMPLEX FOURIER SPACE. More...

Detailed Description

Compute x-gradient in fourier space

Author

IREDELL

Date

96-02-20

Definition in file spgradx.f.

Function/Subroutine Documentation

spgradx()

subroutine spgradx	(	integer, intent(in)	M,
		integer, intent(in)	INCW,
		integer, intent(in)	KMAX,
		integer, dimension(kmax), intent(in)	MP,
		real, intent(in)	CLAT,
		real, dimension(2*incw,kmax), intent(inout)	W,
		real, dimension(2*incw,kmax), intent(out)	WX
	)

THIS SUBPROGRAM COMPUTES THE X-GRADIENT OF FIELDS IN COMPLEX FOURIER SPACE.

THE X-GRADIENT OF A VECTOR FIELD W IS WX=CONJG(W)*L/RERTH WHERE L IS THE WAVENUMBER AND RERTH IS THE EARTH RADIUS, SO THAT THE RESULT IS THE X-GRADIENT OF THE PSEUDO-VECTOR. THE X-GRADIENT OF A SCALAR FIELD W IS WX=CONJG(W)*L/(RERTH*CLAT) WHERE CLAT IS THE COSINE OF LATITUDE. AT THE POLE THIS IS UNDEFINED, SO THE WAY TO GET THE X-GRADIENT AT THE POLE IS BY PASSING BOTH THE WEIGHTED WAVENUMBER 0 AND THE UNWEIGHTED WAVENUMBER 1 AMPLITUDES AT THE POLE AND SETTING MP=10. IN THIS CASE, THE WAVENUMBER 1 AMPLITUDES ARE USED TO COMPUTE THE X-GRADIENT AND THEN ZEROED OUT.

Parameters

	M	- INTEGER FOURIER WAVENUMBER TRUNCATION
	INCW	- INTEGER FIRST DIMENSION OF THE COMPLEX AMPLITUDE ARRAY (INCW >= M+1)
	KMAX	- INTEGER NUMBER OF FOURIER FIELDS
	MP	- INTEGER (KM) IDENTIFIERS (0 OR 10 FOR SCALAR, 1 FOR VECTOR)
	CLAT	- REAL COSINE OF LATITUDE
[out]	W	- COMPLEX(INCW,KMAX) FOURIER AMPLITUDES CORRECTED WHEN MP=10 AND CLAT=0
[out]	WX	- COMPLEX(INCW,KMAX) COMPLEX AMPLITUDES OF X-GRADIENTS

Note

THIS SUBPROGRAM IS THREAD-SAFE.

Definition at line 35 of file spgradx.f.