# vhsec, vhsgc

Procedures for computing vector spherical harmonic syntheses via
Spherepack.

## Synopsis

procedure vhsec(
br : float,
bi : float,
cr : float,
ci : float,
u : float,
v : float
)
procedure vhsgc(
br : float,
bi : float,
cr : float,
ci : float,
u : float,
v : float
)

## Arguments

*br, bi, cr, ci*
- vector spherical harmonic coefficients (input, array with two or
more dimensions, last two dimensions must be
*nlat* x *nlat*
and values must be in ascending latitude order, but see note below)
*u, v*
- vector spherical harmonic synthesis arrays (input/output, same
dimensions as
*br, bi, cr, ci*, except the last two dimensions
must be *nlat* x *nlon* and values must/will be in ascending
latitude order, but see note below)

## Description

**Note: If you have version 4.1 of NCL, these procedures will not
work with arrays greater than two dimensions. In order to use arrays
with more than two dimensions, you need to run version 4.1.1 of NCL.
If your site is licensed for version 4.1, then you can get version
4.1.1 for free. To get version 4.1.1 of NCAR Graphics software, please
contact your site representative. If you don't know who your site
representative is, then send email to ncarginf@ucar.edu or call (303)
497-1201.**

**
***vhsec* and *vhsgc* both perform the vector spherical
harmonic synthesis on the arrays *br*, *bi*,
*cr*, and *ci* and store the results in the arrays
*u* and *v*. *vhsec* operates on an equal
(fixed) grid, and *vhsgc* operates on a Gaussian grid.
For the arrays whose last two dimensions are *nlat* x
*nlon*, the rest of the dimensions (if any) are collectively
referred to as *nt*. If the input/output arrays are just two
dimensions, then *nt* can either be considered equal to 1 or
nothing at all.

Arrays which have dimensions *nt* x *nlat* x *nlon*
should **not** include the cyclic (wraparound) points when invoking
the procedures and functions which use spherical harmonics
(Spherepack).

For example, if an array *x* has dimensions *nlat* = 64 and
*nlon* = 129, where the "129" represents the cyclic points, then
the user should pass the data to the procedure/function via:

z = sample ( x([...],:,0:nlon-2) ) ; does not include cyclic points

## Error messages

If *jer* or *ker* is equal to:
1 : error in the specification of *nlat*

2 : error in the specification of *nlon*

4 : error in the specification of *nt* (*jer* only)

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* $Revision: 1.13 $ $Date: 1999/04/29 21:32:21 $ *