NAME

       CSA2LS - cubic spline approximation, simple entry for two-dimensional input, list output

SYNOPSIS

       CALL CSA2LS (NI, XI, UI, KNOTS, NO, XO, YO, 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  coordinates  of  the  input  data
                   points. XI is dimensioned for 2 x NI.  XI(1,L) is the X coordinate and XI(2,L)
                   is the Y 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 the
                   coordinate (XI(1,L),XI(2,L)) for L=1,NI.

       KNOTS       (integer,  input)  The  number  of  knots  to  be  used  in  constructing  the
                   approximation  spline.   KNOTS is dimensioned for 2 and provides the number of
                   knots to be used in the X and the Y directions.  Both  KNOTS(1)  and  KNOTS(2)
                   must  be  at  least  4.   The  larger  the  values  for  KNOTS, the closer the
                   approximated curve will come to passing through the input function values.

       NO          (integer, input) The number of coordinate values in the output list.   NO  can
                   be any positive number.

       XO          (real,  input) An array dimensioned for NO containing the X coordinates of the
                   output list.

       YO          (real, input) An array dimensioned for NO containing the Y coordinates of  the
                   output list.

       UO          (real,  output) An array dimensioned for NO containing the calculated function
                   values for the output spline.  UO(I) is the  calculated  functional  value  at
                   (XO(I),YO(I)) for I=1,NO.

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

       CSA2LS is called to find an approximating cubic spline surface for  two-dimensional  input
       data  with  output  values  calculated at a list of user-specified points.  If you want to
       weight the  input  data  values,  calculate  derivatives,  or  handle  data  sparse  areas
       specially, then you will need to use CSA2LXS.

ACCESS

       To use CSA2LS, load the NCAR Graphics library ngmath.

SEE ALSO

       csagrid, csa2s, csa2xs, csa2ls,

       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.