NAME

       CURVI - integrate a spline curve

SYNOPSIS

       FUNCTION CURVI (XL, XU, N, X, Y, YP, SIGMA)

       This  function  calculates an integral between two specified limits.  CURV1 must be called
       prior to calling CURVI, and the values thus obtained used as input to CURVI.  The value of
       the integral is returned.

DESCRIPTION

       XL          (real, input) The lower limit of the integration.

       XR          (real, input) The upper limit of the integration.

       N           (real, input) The number of input data values. (N > 1)

       X           (real, input) An array containing the abscissae for the input function.

       Y           (real,  input) An array containing the functional values of the input function
                   -- Y(K) is the (real, input) functional value at X(K) for K=1,N.

       YP          (real, input) Contains values for the  second  derivative  (as  calculated  by
                   CURV1).

       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.

RETURN VALUE

       CURVI returns the integral of the interpolated curve between the specified limits.

ACCESS

       To use CURVI, load the NCAR Graphics library ngmath.

SEE ALSO

       curv1, 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.