Here is source code for the VSPLINE software package, developed at Stanford University by Jeff Fessler.

This software implements algorithms that are described in the following publications

• J A Fessler.
  Nonparametric fixed-interval smoothing with vector splines.
  IEEE Tr. Sig. Proc., 39(24):852-9, Apr. 1991.
• J A Fessler.
  Nonparametric smoothing of nonlinear measurements.
  IEEE Tr. Sig. Proc., 39(4):907-13, Apr. 1991.

You may freely use and distribute this software as long as you retain the author's name (myself and/or my students) with the software, and if you make changes, please change the file name (like the GNU software license).