CSA3S(3NCARG)

NAME
CSA3S - cubic spline approximation, simple entry for three-dimensional input

SYNOPSIS
CALL CSA3S (NI, XI, UI, KNOTS, NXO, NYO, NZO, XO, YO, ZO,
            UO, NWRK, WORK, IER)

DESCRIPTION

NI  (integer,input) The number of input data points. It must be that NI .gt. 3 and, depending on the size of KNOTS below, NI may have to be larger.

XI  (real, input) An array containing the X - Y - Z coordinates of the input data points. XI is dimensioned for 3 x NI. XI(1,L) is the X coordinate, XI(2,L) is the Y coordinate, and XI(2,L) is the Z coordinate for the input domain for L=1,NI.

UI  (real, input) An array dimensioned for NI containing function values at the input XI values, that is, UI(L) is the value of the input function at XI(L) for L=1,NI.

KNOTS
    (integer, input) An array dimensioned for 3 containing the number of knots to be used in each coordinate direction for constructing the approximation spline. KNOTS(I) must be at least 4 for I=1,3. The larger the value for KNOTS, the closer the approximated curve will come to passing through the input function values.

NXO (integer, input) The number of X coordinate values in the output grid.

NYO (integer, input) The number of Y coordinate values in the output grid.

NZO (integer, input) The number of Z coordinate values in the output grid.

XO  (real, input) An array dimensioned for NXO containing the X coordinates of the output surface.

YO  (real, input) An array dimensioned for NYO containing the Y coordinates of the output surface.

ZO  (real, input) An array dimensioned for NZO containing the Y coordinates of the output surface.

UO  (real, output) An array dimensioned for NXO x NYO x NZO containing the calculated function values for the output function. UO(I,J,K) is the calculated functional value at (XO(I), YO(J), ZO(K)) for I=1,NXO and J=1,NYO and K=1,NZO.

NWRK
    (integer, input) The size of the WORK array. NWRK must be at least NK * (NK+3) where NK = KNOTS(1) * KNOTS(2) * KNOTS(3).

WORK
    (real, input) A work array dimensioned for NWRK.

IER (integer, output) An error return value. If IER is returned as 0, then no errors were detected. If IER is non-zero, then refer to the man page for csagrid_errors for details.

USAGE
CSA3S is called to find an approximating cubic spline for three-dimensional input data. If you want to weight the input data values, calculate derivatives, or handle data sparse areas specially, then you will need to use CSA3S.

ACCESS
To use CSA3XS, load the NCAR Graphics library ngmath.

SEE ALSO
csagrid, csa3xs, csa3ls, csa3lxs

Complete documentation for Csagrid is available at URL
http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html

COPYRIGHT
Copyright (C) 2000
University Corporation for Atmospheric Research
The use of this Software is governed by a License Agreement.