cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Showing results for 
Search instead for 
Did you mean: 

Circuit equation

SOLVED
Gravel

Circuit equation

Hello everyone

 

I can not find the solution M of the attached equation. (mathcad 15)

[undefind] is displayed.

 

Please give some advice on what this means.

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Circuit equation

Simply don't use the symbolic evaluation after minerr

B.png

23 REPLIES 23

Re: Circuit equation

Here's an example of circuit analysis with Mathcad:LM_20190726_Circuit.png

(I generally first try to solve symbolically, afterwards I can fill in the numbers)

Success!
Luc

Re: Circuit equation

Hello Luc san

 

Thanks your quick response.

 

I can not solve  symbolically my problem.

 

I attached file.

Re: Circuit equation

Hello Ssato san,

 

I cannot read your file directly,

Please save as Mathcad 11 .mcd file and attach.

(do not care about any warnings when saving).

 

Luc

Re: Circuit equation

Hello Luc san

 

I attached file saved by MATHCAD11.

 

Re: Circuit equation

Because your initial equations are linear in the currents, I1, I2 and I3, they can be rearranged in matrix form and solved as in the attached  (I first manipulated the equations a little before putting them into matrix form).

 

Alan

 

Re: Circuit equation

Simply don't use the symbolic evaluation after minerr

B.png

Re: Circuit equation

According your file look at my previous answer - remove the symbolic eval after minerr.

 

According the last example in Luc's file, you may read the "error" message. There is no error, but Mathcad 15 simply is not able (or willing) to display the large result. Luc's Mathcad 11 uses a much more capable symbolic processor (Maple) and does not have this display problem.

But as the error message says, you still can USE the resulting function!

In this case with a little help from the "simplify" modifier we can even persuade MC to display the symbolic results one by one.

Note that in Luc's sheet ORIGIN is set to 1 and we unfortunately cannot use units when evaluating the functions numerically as the unit system is turned off in this sheet (-> Tools -> Worksheet Options -> Unit System)

B.png

Re: Circuit equation

I think there's an error in your initial sheet: Unless R2 is 0, it's missing from the first equation.

In the sheet you adapted from mine, you included it as R1, I guess because it's meant to be non-zero.

Attached is my analysis of the circuit.

 

LM_20190726_CircuitEquation1.png

LM_20190726_CircuitEquation2.png

Success!
Luc

Re: Circuit equation

Prime 5 Loop method.