Is there a peak width .vi

[eword]

I need to calculate the width of peaks in some data. I am currently using the calculation mentioned at this thread:

http://forums.ni.com/t5/LabVIEW/Peak-Width/m-p/382458?requireLogin=False

however I was just wondering is there any labview .vi or similar?

[eword]

The reason I ask is that using the method supplied in the aforementioned reports my peak widths as being reported as smaller than they actually are.

[altenbach]

How do you define peak width? Width at half height?

Show us some typical data and tell us what width you are expecting.

[eword]

An example is attatched. My software reports a FWHM of the max peak of around 1.8 however the actual peak width is more like 5. Unless I am doing the FHWM calculation incorrectly using the outputs from the peak finder .vi ?? The current calculation I am using is:

2*sqrt(-PEAK Amplitude/y") = Peak Width

which uses the amplitude and second derivative from the peak finder .vi

[altenbach · Accepted solution]

What is the difference between FWHM and FHWM?

You seem to have very few points defining your peak. Are they Gaussian, Lorentzian? Just looking at the graph, a value around 2 seems about correct.

If you think 5 is correct, maybe you want the width at 5% of maximum?

Remember, the full width at half maximum (FWHM) is the width at half the height of the peak (A) and not near the peak base (B) as you seem to think.

[eword]

Ok cheers for that.