Tangent lines in XY graph

[Pukhtun_Yum]

Hello,

I have attached a picture in which i have to find the cutt frequency, the Y axis is the amplitude and X-axis is the frequency.

The red lines in the picture is the tangent lines, how would i make it visible in the graph and find the intersection point of both of it to calculate the cutt off frequency?

Thank you have and stay healthy.

[GerdW]

Hi Pukhtun,

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@Pukhtun_Yum wrote:

The red lines in the picture is the tangent lines, how would i make it visible in the graph and find the intersection point of both of it to calculate the cutt off frequency?

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This is rather basic math knowledge!

Determine slope/intersection of both tangent vectors. (You may use some interpolation function on a subset of your plot point data.)

Then calculate their crossing point. (You may use some of those mathematics functions…)

What have you tried so far? Where are you stuck?

[Pukhtun_Yum]

I tried it but could not find the correct VIs to implement the method.

How can i take two lines from a single graph ?

It seems to be quiet confusing for me

[GerdW]

Hi Pukhtun,

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@Pukhtun_Yum wrote:

How can i take two lines from a single graph ?

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I repeat: "use some interpolation function on a subset of your plot point data"

See this:

As you use a logarithmic X axis it might help to apply a log() function on the X data before interpolation…

[altenbach]

Maybe you can find a mathematical model that describes your curve and fit to it after which you can determine  the interesting parameter.

[alexderjuengere]

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@GerdW wrote:

See this:

As you use a logarithmic X axis it might help to apply a log() function on the X data before interpolation…

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nice!