# LabVIEW

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## Distance between two minimum

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)?

Message 1 of 9
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## Re: Distance between two minimum

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!

Best regards,
GerdW

using LV2011SP1 + LV2017 (+LV2020 sometimes) on Win10+cRIO
Message 2 of 9
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## Re : Distance between two minimum

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

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Message 3 of 9
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## Re : Distance between two minimum

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?

Message 4 of 9
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## Re : Distance between two minimum

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!)

Best regards,
GerdW

using LV2011SP1 + LV2017 (+LV2020 sometimes) on Win10+cRIO
Message 5 of 9
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## Re : Distance between two minimum

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

Message 6 of 9
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## Re : Distance between two minimum

@IlDama wrote:

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

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

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The best way to say thanks is to give kudos!
Message 7 of 9
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## Re : Distance between two minimum

I can't, look at my code!

Message 8 of 9
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## Re : Distance between two minimum

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!

Best regards,
GerdW

using LV2011SP1 + LV2017 (+LV2020 sometimes) on Win10+cRIO
Message 9 of 9
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