Does my "model description" need to be accurate?

[Sametron]

Hi,

I am new to this forum, so please let me know if this question is being posted in the wrong category and where might be a better place to ask if there is one.

I am using a non-linear fit VI to fit some data points, and I am using a "model equation" rather than a VI for the function.

Because the function is a transfer function I am leaving off the phase and just plotting the magnitude of the real, which comes out as a complicated function, nevertheless, I enter it in the field on the front panel and am getting "bracket", "wrong letter", and "wrong model equation" errors. I have already completed a fit for a different VI but with a much simpler equation, so my method is correct I think; it seems the problem is my equation. I guess my first question is, which error appears first? eg, if my result is "wrong model description", does that indicate my syntax is correct (no bracket or variable issues) and that my equation just doesn't fit the curve? Is there any way to enter a simpler form of my equation, maybe something on the same order, and slowly work towards my complex equation?

Thanks

[Sarci1]

Hello Sametron,

If you are using the model equation, my suggestion would be to check out Using the Nonlinear Curve Vit VI for help on syntax.  With regards to the errors you are receiving, try wiring a Simple Error Handler VI (Functions palette>>Programming>>Dialog and User Interface>>Simple Error Handler) to the output of the curve fitting.  This will capture all of those errors in order and also display the error codes that we use for debugging.

Lynn