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# Multivariable algebrain equations2

## Multivariable algebrain equations

(OP)
I'm trying to do Castigliano's theorem in Mathcad. Integrating in Mathcad is pretty easy, but is there a way to implicitly define functions?

For example, I would like to be able to enter

-M + F*0.026m + Q*0.036m = 0

(which is a force balance on a free body diagram)

and let Mathcad turn the above expression into

M = F*0.026m + Q*0.036m

so that it's an explicit expression for M, a moment term.

Is this possible? Or do I have to write out the steps manually?

### RE: Multivariable algebrain equations

shimo,

1) Write out your original expression, using the Ctrl= (the bold equal sign).
2) Highlight the variable you are interested in solving for.
3) Select  Symbolics -> Variable -> Solve
4) Mathcad will display the solution.  You will have to provide the "M :=" at the beginning of it.

Good luck

Pete

### RE: Multivariable algebrain equations

(OP)
Awesome, thanks.

But is it possible to make Mathcad define the separated variable M as the explicit function? I'd like Mathcad to output something like

M(Q) = F*0.026m + Q*0.036m

where F is a constant.

Doing it by hand is like 1 extra line, but it would look a lot cleaner if I could do it automatically.

Also, what's the function of the Boolean equal sign here? I don't understand how to use them.

### RE: Multivariable algebrain equations

(OP)
Thank you! That Mathcad file really helped a lot.

### RE: Multivariable algebrain equations

excognito,

Great solution - I was not familiar with live symbolics 'til you showed it in your worksheet.

Pete

### RE: Multivariable algebrain equations

Yes, live symbolics are very useful.  However, you have to be aware that symbolics don't pay any attention to units (treated as variables - however, this can useful in certain circumstances), don't fully mirror the functionality of the numerics (eg, rand) and run noticeably slower than numeric calculations in general.

### RE: Multivariable algebrain equations

Yes, live symbolics are very useful.  However, you have to be aware that symbolics don't pay any attention to units (treated as variables - however, this can useful in certain circumstances), don't fully mirror the functionality of the numerics (eg, rand) and run noticeably slower than numeric calculations in general.

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