NAME

       CURVS2  - calculates an interpolated value for a smoothing spline under tension at a given
       point.

SYNOPSIS

       FUNCTION CURVS2(T,N,PARAM,X,Y,XP,YP,SIGMA,XO,YO)

       This subroutine is a companion  to  CURV1S  which  must  be  called  before  calling  this
       subroutine.   CURV2S calculates an interpolated value for a smoothing spline under tension
       at a given point.

DESCRIPTION

       T           (real, input) A real value to be mapped onto the interpolating curve.   Values
                   of  T  between  zero  and  one  interpolate the original data; any values of T
                   outside this range result in extrapolation.

       N           (integer, input)  The number of points which were specified to  determine  the
                   curve in CURVS1.

       PARAM       (real, input) The arc lengths as computed by CURVS1.

       X           (real,  input)  An  array  containing the X-coordinate values of the specified
                   points.

       Y           (real, input) An array containing the Y-coordinate  values  of  the  specified
                   points.

       XP          (real, input) An array of second derivative values as calculated by CURVS1.

       YP          (real, input) An array of second derivative values as calculated by CURVS1.

       SIGMA       (real, input) Tension factor. Values near zero result in a cubic spline; large
                   values (e.g. 50) result in nearly a polygonal line. A typical value is 1.

       XO          (real, output) The interpolated X value.

       YO          (real, output) The interpolated Y value.

ACCESS

       To use CURV2, load the NCAR Graphics library ngmath.

SEE ALSO

       curvs1, fitgrid_params.

       Complete documentation for Fitgrid is available at URL
       http://ngwww.ucar.edu/ngdoc/ng/ngmath/fitgrid/fithome.html

COPYRIGHT

       Copyright (C) 2000
       University Corporation for Atmospheric Research

       The use of this Software is governed by a License Agreement.