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09-10-2020
02:00 PM

09-10-2020
02:00 PM

How to plot complex impedances where it is a product of 2 complex functions

Impedances of a capacitor Zc = 1/s*c(s) and the unit is Farad

where s is the Laplace Domain variable = 1j*w = 1j*2*pi*frequency

in my case, c(s) is the capacitance but is a function of s

I want to plot the magnitude of Zc = {[Re(Zc)]^2+[I'm(Zc)]^2}^0.5 versus frequency

If Zc is evaluated with "=", the result returns a scalar

I asked PTC helps and they said it is because I have 2 vectors multiplied together, so it returns a scalar. They recommend to vectorize the Zc expression but if you do that, it return a complex impedances of 1000 frequencies (the # of points I have), and then find a way to convert the 1000 complex impedances into the magnitude of each of the 1000 complex impedances.

My question is: Why do I have to vectorize the Zc expression? Is there another way to do it that does not need to vectorize Zc? I find it hard to believe when you want to plot out the magnitude or phase of a complex function that contains a product of more than 2 functions, you have to vectorize it.

Please see attached file

Thanks a lot for your helps

Rdliquid

PS: I am using Mathcad Prime 6.0

Solved! Go to Solution.

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09-10-2020
03:20 PM

09-10-2020
03:20 PM

Hi Werner_E,

Thanks a lot for your helps. You answered my questions. OK I will vectorize(---->) and absolute | | the expression from now on

Rdliquid

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09-10-2020
02:35 PM

09-10-2020
02:35 PM

Re: plotting complex impedances

The attached sheet should help and explains why vectorization is needed.

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09-10-2020
03:20 PM

09-10-2020
03:20 PM

Hi Werner_E,

Thanks a lot for your helps. You answered my questions. OK I will vectorize(---->) and absolute | | the expression from now on

Rdliquid

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09-11-2020
07:11 PM

09-11-2020
07:11 PM

Re: plotting complex impedances

Hi

I though I understand vectorization until I ran into this strange issue. Can you explain:

H(s) is a complex function

G(s) is a vectorized of H(s)

Each one returns a different result. Do you know why?

Please see attached

Thanks again,

Rdliquid

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09-11-2020
07:51 PM

09-11-2020
07:51 PM

Re: plotting complex impedances

@rdliquid wrote:

Hi

I though I understand vectorization until I ran into this strange issue. Can you explain:

H(s) is a complex function

G(s) is a vectorized of H(s)

Each one returns a different result. Do you know why?

Sure!

R.s/z.dsl and z.d5ls/R.l are both vectors and without vectorization the product is calculated as vector product which obviously is not what you intended.

If you want an expression containing vectors to be evaluated elementwise you should always use vectorization.