Re : Distance between two minimum

[IlDama]

Hi everyone,

the file below represents my incomplete code. How can i find the distance between the two minimum of my interpolated curve (represented in the image below)?

[GerdW]

Hi IIDama,

so you have a polynomial and want to know its minima?

Usually you differentiate the polynomial to calculate the min/max points:

y = sum( a_i * x^i) will differentiated to y' = sum (a_i * i * x^i-1).

As you know the polynomial coefficients it should be quite easy to calculate!

[ben64]

You can use the Peak Detector.vi and set it to detect valleys. It will give you the location of the valleys found. You may have to do a bit of interpretation but it is well explained in the help file.

Ben64

[IlDama]

Hi ben64,

i've already tried to use Peak Detector but my problem is that i don't know how to connect it to my code. Can you help me?

[GerdW]

Hi IIDama,

Have you tried it as simple as this?

(It might work better once you use a real waveform and provide usable settings at the other inputs of the PeakDetector!)

[IlDama]

I want to find the minimum from an XYGraph, this solution doesn't work for it.

[ben64]

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@IlDama wrote:

I want to find the minimum from an XYGraph, this solution doesn't work for it.

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Don't do it on the XY Graph, use it on the Waveform Graph. Then you can retrieve the corresponding points on the XY Graph. Have you set the peaks/valleys input to valleys? set a threshold (and tried different values)?

Ben64

[IlDama]

I can't, look at my code!

[GerdW]

Hi IIDama,

I can't, look at my code!

Why can't you? With all the suggestions you already got?

You got your plot of the polynom. Create a waveform with the data of this plot. Feed the waveform into PeakDetector. Set the parameters for PeakDetector and you will get the desired results!