NAME

       CSA1S - cubic spline approximation, simple entry for one-dimensional input

SYNOPSIS

       CALL CSA1S (NI, XI, YI, KNOTS, NO, XO, YO, 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 dimensioned for NI containing the X coordinates of  the
                   input data points.

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

       KNOTS       (integer,  input)  The  number  of  knots  to  be  used  in  constructing  the
                   approximation spline.  KNOTS must be at least 4.  The  larger  the  value  for
                   KNOTS,  the  closer  the  approximated  curve will come to passing through the
                   input function values.

       NO          (integer, input) The number of values to be calculated for the output curve.

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

       YO          (real,  output) An array dimensioned for NO containing the calculated function
                   values for the output curve.

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

       CSA1S  is called to find an approximating cubic spline for one-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 CSA1XS.

ACCESS

       To use CSA1S, load the NCAR Graphics library ngmath.

SEE ALSO

       csagrid, csa1xs, csa1ls, csa1lxs

       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.