Fitgrid is a package
in the ngmath library
for interpolating one-dimensional and two-dimensional
data. The package has the following functionality:
- Interpolating single-valued functions in one dimension.
- Interpolating parametric curves in the plane.
- Computing an interpolatory surface through a rectangular grid
of functional values.
- Interpolating periodic functions in one dimension.
- Finding integrals and derivatives of interpolated functions.
See the comparative
analysis of the ngmath packages for details
on which ngmath package is most appropriate for your problem.
The functions in Fitgrid utilize splines under tension for the
interpolations. Splines under tension are controlled by a scalar
tension factor that can be adjusted to provide a smooth transition from
cubic spline interpolation to linear interpolation. To do its
interpolations,
Fitgrid fits a tension spline to the input data and then picks its
interpolated values from the fitted spline function.
The documentation for
Natgrid contains a
general discussion of
interpolation algorithms.
Fitgrid is based on
Alan
Cline's package Fitpack, an early version of which is available
from netlib. Fitpack
uses splines under tension to interpolate in one and two dimensions.
An expanded version of Fitpack, as well as complete hardcopy documentation,
can be obtained from: Pleasant Valley Software, 8603 Altus Cove,
Austin TX 78759. Dr. Cline has our great gratitude for allowing us to
incorporate his early version of Fitpack into the ngmath library.
You should now proceed to the module on
learning how to use Fitgrid.
© University Corporation for
Atmospheric Research 1997-99.
All rights reserved.
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