polynomial fits

[havenoidea]

I need to do a simple 2D polynomail fits (linear and parabola). Is there any vi's I can use to obtain the best fits with errors?

[altenbach]

Sorry, are you just looking for a polynomial fit with 1 independent variable (xy) giving you a line curve  or with 2 independent variables, giving you e.g. a parabolic plane.

for the first case, there is a plain polynomial fit, but unfortunately it does not give you parameter errors.

However, both (1D and 2D) are simple linear systems so you should be able to setup a H matrix and use "general LS fit" from the fitting palette. One of the outputs is the covariance matrix which will let you calculate the parameter error from the diagonal elements.

For a comparison of a 2D polynomial and levenberg Marquardt fit, have a look at my example:

http://forums.ni.com/ni/board/message?board.id=170&message.id=129944#M129944

The code shows how to setup the H matrix for a polynomial with 2 independent variables. For a simple polynomial with one independent variable it is even much simpler.

Let me know if you need more help.