1. rbf
  2. Documentation
    1. Datatypes
      1. RBFInterpolant
    2. Procedures
  3. Examples
  4. About this egg
    1. Author
    2. Repository
    3. Version history
    4. License

rbf

Bindings to Multidimensional Interpolation with Radial Basis Functions by John Burkardt.

Documentation

Datatypes

RBFInterpolant

A record representing a radial basis function interpolant. Fields:

rank
The spatial dimension
basis
The type of basis function used
scale
The scale factor for the basis functions
npoints
The number of data points
xpoints
The data points (f64vector)
weights
The computed weights (f64vector)

Procedures

[procedure] make-interpolant :: basis m scale xpoints ypoints -> RBFInterpolant

Creates a new RBF interpolant. Parameters:

basis
Symbol representing the basis function type:
- 'mq or 'multiquadratic: Multiquadratic basis
- 'imq or 'inverse-multiquadratic: Inverse multiquadratic basis
- 'tp or 'thin-plate: Thin plate spline basis
- 'ga or 'gaussian: Gaussian basis
m
Integer specifying the spatial dimension
scale
Real number specifying the scale factor. Should be larger than the typical separation between points, but smaller than the maximum separation.
xpoints
f64vector containing the data points (length should be m × number_of_points)
ypoints
f64vector containing the function values at the data points (length should equal number_of_points)

Returns a new <RBFInterpolant> record.

[procedure] eval-interpolant :: RBFInterpolant ipoints -> f64vector

Evaluates the interpolant at the specified points. Parameters:

interpolant
An RBFInterpolant record created with make-interpolant
ipoints
f64vector containing the interpolation points (length should be m * number_of_interpolation_points)

Returns a f64vector containing the interpolated values at the specified points.

Examples

 
(import rbf srfi-4)

;; Create a 2D interpolant with 4 data points
(define x-data (f64vector 0.0 0.0  0.0 1.0  1.0 0.0  1.0 1.0))
(define y-data (f64vector 0.0      0.0      0.0      1.0))

;; Create an interpolant using Gaussian basis functions
(define interpolant (make-interpolant 'ga 2 0.5 x-data y-data))

;; Evaluate at a specific point (0.5, 0.5)
(define query-point (f64vector 0.5 0.5))
(define result (eval-interpolant interpolant query-point))

;; Print the result
(print (f64vector-ref result 0))

About this egg

Author

Ivan Raikov

Repository

https://github.com/iraikov/chicken-rbf

Version history
1.0
Initial release

License

 
Copyright 2019-2025 Ivan Raikov.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

A full copy of the GPL license can be found at
<http://www.gnu.org/licenses/>.