Learn more about Spline Toolbox

Construction and Use

You are most likely to construct such a form by looking for an interpolant or approximant to gridded data. For example, if you know the values , of some function at all the points in a rectangular grid, then, assuming that the strictly increasing sequence x satisfies the Schoenberg-Whitney conditions with respect to the above knot sequence , and that the strictly increasing sequence y satisfies the Schoenberg-Whitney conditions with respect to the above knot sequence , the command

constructs the unique bivariate spline of the above form that matches the given values. The command fnplt(sp) gives you a quick plot of this interpolant. The command pp = fn2fm(sp,'pp') gives you the ppform of this spline, which is probably what you want when you want to evaluate the spline at a fine grid ((xx(i),yy(j)) for i=1:M, j=1:N), by the command:

values = fnval(pp,{xx,yy});

B-form

ppform

© 1984-2009- The MathWorks, Inc.    -   Site Help   -   Patents   -   Trademarks   -   Privacy Policy   -   Preventing Piracy   -   RSS