B-Spline Fit Lockup

[BillView]

Hello,

I've implemented the B-Spline fit function to find a normalization curve. With particular data sets, the program gets hung up in the library call to NI_AALPro.lvlib:B-Spline Fit _nD .vi and ctrl alt delete is the only way to escape. After changing the order of the polynomial fit or the number of control points it still gets hung up on the data set.

I'm running Labview 2009 with the full development package, version 9.0f2.

Is this user error? If not, does it look like a bug in the curve fitting routine? And does anyone know how to identify a problematic data set before the hang up occurs?

Attached is a sample of code with a data set that causes labview to lock up, so be sure you're saved up if you run it!

Thanks for looking!

-Bill

[xearthl]

Hi BillView,

It has been proved to be a bug and we will fix it in our next release.

Thanks a lot for reporting this to us!

xearthl

[hongqin]

I am using 8.6.2. With spline intepolation, it also locks up. Just want to know if this bug is fixed or not. Here is where it hangs. Any get-around solutions?

Thanks 

.

[iZACHdx]

Hello,

This is filed under CAR #211011 and has not been fixed in any current releases. You can check the release notes for the CAR number to verify that is has been fixed with a particular relase.

-Zach

[ben64]

The error is caused by your last pair of points. It seems that the algorithm is waiting for another pair to compute the i'th B-Spline pair. If you don't use the last pair as showed in the snippet the vi will not hangup.

Ben64

[ben64 · Accepted solution]

I looked more closely at your 2 last data points and found out that they have the same x value. By changing the last x value at the 6th decimal no hangup occur.

Ben64

[BillView]

Thanks Ben!

[BillView]

A note for anyone stumbling across this...

It seems that you don't necessarily need a 1:1 data set, as long as the last two x data points don't match.  For example the data set in the attachment has 80 consecutive matching x values in the input array, but the only pair that the function gets hung up on is the last one.  

[Jon_S.]

CAR 211011 has been fixed in LabVIEW 2010.  For more bug fixes please consult the LabVIEW 2010 Readme.