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Insert a tangent line into a plot

Hi everyone,

I want to know if it is possible to insert a tangent line into a plot, tangent to it, with a certain slope and at certain (x,y).

Regards.

Andrew Beckett over 8 years ago

How about using the tangent function in the calculator?

Regards,

Andrew.
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CESA over 8 years ago

Hi Andrew, thank you for the suggestion. I have tried that and what I get is not a curve with the slope I want. I get a simple horizontal line with its y-value equal to the slope.
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Andrew Beckett over 8 years ago

That wasn't how it behaved when I used it. You provide a waveform (signal) as the input so that it can use the same x-axis points, an x and y intercept point, and a slope - having done that, it worked perfectly for me.

Which IC subversion are you using (what does getVersion(t) return in the CIW, or the Help->About window say?)

Regards,

Andrew.
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CESA over 8 years ago

I have tried that. The input, as for an example, is the mosfet Ids vs Vgs characteristic. Sub-version .500.12.

Thanks.
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Andrew Beckett over 8 years ago

There are probably at least 6 major versions with that subversion (spanning 10 years). What is the full subversion number? Then I'll check and put together a small example.

Regards,

Andrew.
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CESA over 8 years ago

Sorry Andrew. It pasted only half of the text. This is the sub-version: IC6.1.6-64b.500.12.

Thanks for your help.

Regards.
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Andrew Beckett over 8 years ago

No problem - it happens.

I just tried in that version. To make it nicer, I used the value() at my desired intercept point so that it intersected the line (this is a DC sweep of VGS for a transistor):

Regards,

Andrew.
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CESA over 8 years ago

Andrew, thanks. Still not get the tangent curve I want. I didn't tell you but I am using the waveform function as well because I want to have a different x-axis value. Could this be the problem?
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Andrew Beckett over 8 years ago

Can you share what you're actually doing? i.e. the expression you're trying to use - a screenshot of the curves, and so on? Otherwise I'm stabbing in the dark here...

Andrew
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CESA over 8 years ago

EDIT: Andrew I managed to find the problem. I have forgotten to put the e-5.

Thanks for the help.
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