problem with interpolation

[WeberM]

I've got a problem. In my VI there are three different kinds of interpolation. Fpr ma the best interpolation is the Rat.-Interpolation.
But in this Interpolation there are extreme errors. Why?
I need an Interpolation which gives me a
x- and y- value back.

[JCC_(SK)]

Hi,
your interpolation are with extreme errors because you have bad interpolation function (you need high polynomial order) and your interpolation data are complicated.

You can try different type of interpolation {no only linear and quadratic}

Look my examples, and example in LV: \LabVIEW 7.1\examples\math\optimiz.llb\Parameter Fitting LM.vi

Best regard
JCC

[WeberM]

Thank's for this example.
But how do i get my y-value from a defined x-value?

markus

[JCC_(SK)]

Hi Markus,

when you use to interpolation function y = a + b * x as in "General Polynomial Fit.vi" with 'polynomal order' = 2 . You must recalculate you require X values over this function.

Or when you want use complicated polynomial {or other } function you can use Formula Node. Look my second part of example. It looking terribly, but it working, and you can use complicated interpolation function.

Have nice day
JCC