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Ocean/Calculator expressions and their units

MicheleA

Hi all,

I know it's not advised to put more than one questions per post, however I hope I'll structure this such that there won't be no confusion.

Main Topic

I am defining some expressions I would like to assess in my designs. To this end, I use the calculator in conjunction with some "ocean" script...Actually I just write expressions and define variables on a plain text file, but the idea is to expand on that with plotting functions and maybe output to file.

So let's say I have an AC sim. I then define some curves as follows:

 

twoPi = 44.0/7.0

vtank = VF("/tank_pos")-VF("/tank_neg")

itank = IF("/Vgen/MINUS")

icap = IF("/Cprobe/PLUS")

icapfix = IF("/Cfprobe/PLUS")

iind = IF("/Lprobe/PLUS")

runfreq = xval(vtank)

Ytank = itank/vtank

Zcap = vtank/icap

Zcapfix = vtank/icapfix

Zind = vtank/iind

cap = 1/(-twoPi*runfreq*imag(Zcap))

 

Now, it all works good if I copy/paste these definitions in the CIW, then ask --> plot(cap)

The issue I have with this is that now the Y-axis shows "freq" units...

cap value in femtohertz?

I observed that runfreq, defined as xval, is still correct. But if I do 1/runfreq, what I get is something with units of 1/(1/Hz), instead of s.

So probably here's where it loses it. Anyways, I see two possibilities here:

 

  1. I am doing it wrong
  2. I am doing it right

 

If 1 holds, then what's the right approach for something like this?

If 2 holds, do I have a way of "forcing" units onto expressions?

--------------------------------------------------------------------------------------------- END ----------------------------------------------------------------------------------------- 

Side Topic

 I find it more comfortable to write my expressions in the text editor rather than inputting them in the output definition box of ADE or ADE-XL. Is there a way of having the environment read my definitions as a file, and then just output the final expressions? In the (simple) case at hand, I would have defined all expressions as above, and plot them either from the CIW or directly from the file...

 

Thanks for your help!!

 Michele

Parents

  • Hi Andrew,

    thanks again, I did as instructed and it works just fine. Nice tip for the user defined functions in the Calc (yes...I'm a newbie in all that).

    There is still a detail I don't quite get, however. Referring to the variables I defined as pasted in the opening post, the curve "cap" for instance is plotted as follows (after passing through abSetUnits())

     

    ...so instead of saying "cap (fF)" in the Y axis, or C(fF), somehow the software sees this curve as of type "freq".

    Since you said - at the beginning - that the units do get preserved, even if not reduced, I don't understand what is going on:

    vtank is a (complex) voltage

    icap is a (complex) current

    Zcap is a complex impedance 

    runfreq is a frequency

    twoPi is a number

    cap= 1/(twoPi*runfreq*Imag(Zcap))

    cannot be a "freq", because runfreq is at the denominator... 

    Can you explain me how that comes, what am I doing incorrectly? I don't want to bother you too much...If you want to point me to a specific part of the (sea of) manuals, I'd be glad to do some homework to show my good will ;-)

     Regards,

    Michele 

Reply

  • Hi Andrew,

    thanks again, I did as instructed and it works just fine. Nice tip for the user defined functions in the Calc (yes...I'm a newbie in all that).

    There is still a detail I don't quite get, however. Referring to the variables I defined as pasted in the opening post, the curve "cap" for instance is plotted as follows (after passing through abSetUnits())

     

    ...so instead of saying "cap (fF)" in the Y axis, or C(fF), somehow the software sees this curve as of type "freq".

    Since you said - at the beginning - that the units do get preserved, even if not reduced, I don't understand what is going on:

    vtank is a (complex) voltage

    icap is a (complex) current

    Zcap is a complex impedance 

    runfreq is a frequency

    twoPi is a number

    cap= 1/(twoPi*runfreq*Imag(Zcap))

    cannot be a "freq", because runfreq is at the denominator... 

    Can you explain me how that comes, what am I doing incorrectly? I don't want to bother you too much...If you want to point me to a specific part of the (sea of) manuals, I'd be glad to do some homework to show my good will ;-)

     Regards,

    Michele 

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