w3ft21.f File Reference

Computes 2.5 x 2.5 n. More...

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Functions/Subroutines
subroutine	w3ft21 (fln, gn, pln, eps, fl, work, trigs, l1, l2, i2)
	Computes 2.5 x 2.5 n.

Detailed Description

Computes 2.5 x 2.5 n.

hemi. grid-scaler.

Author

Ralph Jones

Date

1981-11-19

Definition in file w3ft21.f.

Function/Subroutine Documentation

w3ft21()

subroutine w3ft21	(	complex, dimension (31,31)	fln,
		real, dimension (145,37)	gn,
		real, dimension (32,31)	pln,
		real, dimension (992)	eps,
		complex, dimension (31)	fl,
		real, dimension (144)	work,
		real, dimension (216)	trigs,
			l1,
			l2,
			i2
	)

Computes 2.5 x 2.5 n.

hemi. grid of 145 x 37 points from spectral coefficients in a rhomboidal 30 resolution representing a scalar field. Special version of w3ft08() which gives programmer more control of how many waves are summed and how many points in each wave. A programmer can simulate 24-mode, 12-mode, etc.

Program History Log:

Date	Programmer	Comment
1981-11-19	Ralph Jones	Initial.
1984-06-01	Ralph Jones	Change to ibm vs fortran.

Parameters

[in]	FLN	961 complex coeff.
[in]	PLN	992 real space for legendre polynomials
[in]	EPS	992 real space for coeffs. used in computing pln.
[in]	FL	31 complex space for fourier coeff.
[in]	WORK	144 real work space for subr. w3ft12()
[in]	TRIGS	216 precomputed trig funcs, used in w3ft12(), computed by w3fa13()
[in]	L1	Starting wave number
[in]	L2	Ending wave number
[in]	I2	Mode of spectral coefficients
[out]	GN	(145,37) grid values. 5365 point grid is type 29 or 1d hex o.n. 84

Note

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.

Author

Ralph Jones

Date

1981-11-19

Definition at line 40 of file w3ft21.f.