phase plotting

[Marius_P]

Hello,

I am some difficulties with the phase plotting of a transfer function, and I am wondering if you could give me please some pieces of advice.

Attached is the mathcad prime 7 file with the transfer function and the formula for the phase.

I would like to do the plot as described in the attached image.

F represents the ratio f/fo.

Thank you.

[Werner_E]

You forgot to set the axis limits accordingly!

Actually you had set the limits but at the y-axis they were set just to run from 0.91 to 1, which (should) shows just a very tiny part of the expected curve (actually as of Prime limitations/inabilities it doesn't show - only if you limit the x-axis to something like from 0.4 to 0.5).

You may set the first, second and last value at each axis to meaningful values or you may delete these values and let Prime chose an appropriate scale. The latter usually is not the best idea as Prime isn't good at auto-scaling,  but in your example you get a decent plot you can start working with.

If you just want to compare plots with varying Q-value as in the pic you posted, it may be convenient to define an auxiliary function

[Marius_P]

Thank you Werner for your feedback.

I know that atan2(x,y) returns the result in radians, so by just placing the degree symbol between the brackets, will the result be converted automatically? 

[Werner_E · Accepted solution]

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@Marius_P wrote:

Thank you Werner for your feedback.

I know that atan2(x,y) returns the result in radians, so by just placing the degree symbol between the brackets, will the result be converted automatically? 

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Yes, thats what the unit placeolders are for. As you can see in the plot the y-axis scaling is now in degree.

Instead of using the degree symbol from the unit menu you may also simply type "deg" (without the quotes). Unfortunately (unlike in Mathcad) Prime does not allow to use the degree symbol from the keyboard.

Its one of the benefits of using Mathcad or Prime that it can deal almost naturally with units and this includes pseudo-units as radians or degrees as well.

So whenever you do calculations using Prime you should include proper units as Prime will also help you to avoid unit mismatches or the like.

[Marius_P]

Thank you Werner!