gradsf, gradsg

Given array z, compute its gradient via Spherepack.


    procedure gradsf(
        z   : float,
        gzx : float,
        gzy : float

    procedure gradsg(
        z   : float,
        gzx : float,
        gzy : float


array to compute gradient of (input, two or more dimensions, last two dimensions must be nlat x nlon and input values must be in ascending latitude order).
gzx, gzy
gradient arrays (output, same dimensions as z, values will be in ascending latitude order)


gradsf and gradsg both compute the gradient given the array z and return the results in the arrays gzy and gzy. gradsf operates on an equal (fixed) grid, and gradsg operates on a Gaussian grid.

Note: 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

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: 1.8 $ $Date: 1999/02/23 15:59:23 $