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Oct 13, 2011
08:05 AM

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Oct 13, 2011
08:05 AM

Simultaneous equation symbolic solver problem

I am trying to use the symbolic solver in Mathcad to solve three simultaneous equations. I have done this using the numeric solver and am trying to check the results.

The attached sheet shows my attempt at this, but when I insert values for the variables I get different answers depending on which equation I use. I think the way I am trying to use the solver allows Mathcad to take values from the wrong place.

I would be extremely grateful if anyone can help.

Many thanks,

Sam

2 REPLIES 2

Oct 14, 2011
08:33 AM

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Oct 14, 2011
08:33 AM

Unfortunately, I'monly going to confuse the issue further.

If you put the three equations into a matrix (3 X 1), then you can solve for a 3 X 1 matrix of RL, RU, and Pw; The result "is too large to display, but can be used if assigned to a function. In the attached sheet (rev A) I have done that, look for the red.

That function can be evaluated for your conditions. It does not, however, give the results you plotted.

There was a discussion about how to raise the size of what could be displayed. I can see the expressions for RL and RU, but Pw is still too large.

Good luck!

F

Oct 17, 2011
03:52 AM

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Oct 17, 2011
03:52 AM

Hi,

Attached is a sheet with symbolic equations assigned to supplementary variables.

Hopefully I haven't disturbed the basic (initial) equations, but there are 2 differences noted in the results.

Without knowing the derivation its difficult to say if these are 'correct' but the R.l & R.h values are matched so a step closer.

Hope this helps

Regards

Andy