Newbie Question(s) - Some Frustrations

Question

HiFirst of all I am not a mathmatican, so please be gentle with any explanation. I have poured over the manuals and examples but they either get to the numerical answer too soon or don't seem to cover the way I would like to approach the problem!I want to use Mathcad to provide me with a way of making the graphing and solving of networks of electrical impedances very much easier than on paper.So far I have used 'solve' blocks to find n unknown currents from n simultaneous equations, either as numbers or as functions of a variable. Great!However use of the symbolic answer involves cutting and pasting it to use in in further expressions, this is not very 'smooth' and of course stops Mathcad being 'live', so:Q1 = Is there a way of taking the output from a 'solve block' and using it in further calculations, ie Find(i1,i2,i3)-> gives a nice matrix but in the next line I want to use i1, in another formula, say, Rin = Vin/i1 -> This doesn't seem to work, should it, and I am doing something wrong or is there a better way? I suspect that there is as Mathcad told me at one point that the answer was too long to print and I should.... (but I lost the text so no clues!)Q2 = To keep the solve equations short I am using Z1, Z2, etc, to represent impedances so my answer is in terms of i1= some function of Z1, Z2, Z3 etc. But now I have that equation I want to exchange the Zs for 1/2pifC and 2pifL etc. But there seems to be no way of saying Z1 = 1/2pifC, etc and having Mathcad make the substitution symbolically. I can do that with pen and paper but Mathcad seems to fight shy of it!I can upload a file but as this is my first post I thought I'd see what happens first. Any pointers to examples on the web gratefully accepted!Many ThanksStuart

RichardJ · Accepted Answer

Q1 = Is there a way of taking the output from a 'solve block' and using it in further calculations, ie Find(i1,i2,i3)-> gives a nice matrix but in the next line I want to use i1, in another formula, say, Rin = Vin/i1 -> This doesn't seem to work, should it, and I am doing something wrong or is there a better way? I suspect that there is as Mathcad told me at one point that the answer was too long to print and I should.... (but I lost the text so no clues!)

You can combine a numeric assignment with a symbolic evaluation. For example:

Currents(Z1,Z2,Z3):=Find(i1,i2,i3)->

Note that Currents is defined a function of the undefined variables that are on the RHS of the symbolic evaluation.

Q2 = To keep the solve equations short I am using Z1, Z2, etc, to represent impedances so my answer is in terms of i1= some function of Z1, Z2, Z3 etc. But now I have that equation I want to exchange the Zs for 1/2pifC and 2pifL etc. But there seems to be no way of saying Z1 = 1/2pifC, etc and having Mathcad make the substitution symbolically. I can do that with pen and paper but Mathcad seems to fight shy of it!

Look up the symbolic keyword "substitute".

LouP · Answer

There are techniques that can help with circuit analysis, but what makes sense depends on the type of circuits you are trying to analyze (arbitrary, passive filters, nonlinear, etc.) and the level of complexity. Post your sheet so we have some idea of where you are.

Lou

Sign up

Please use your PTC eSupport account.

Welcome to the PTC Community

Please use your PTC eSupport account.