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## Solving for any one Variables in a Single Engineering Equation Like HP Calculator HP Solver  6-Contributor

## Solving for any one Variables in a Single Engineering Equation Like HP Calculator HP Solver

I have enter many equations into a  folder on my HP Calculator and solve problems by jumping from equation to equations one at a time.  I provide a value for all variables in the equations expect one and solve for the unkown by selecting the SOLVE command.

For example:

Power=Flow*TDH*SG/(3960*Eff)

The HP solver provides a list of all varialbles:

Power, Flow, TDH, SG, EFF:  Enter any (4) and solve for the latter.

I would like to enter the equation into MathCad Prime 6.0: and solve for any one of the unknown.

7 REPLIES 7  23-Emerald III
(To:Ben_Hagler)

Like this: Success!
Luc  6-Contributor
(To:LucMeekes)

Luc,

Thanks for you assistance..

I have several follow-up questions but.. I need to get this method to work.. I

I am having difficulty in getting this to work.  Not sure what I am doing wrong.

Defining Equation EQpower:=Power=Flow*TDH*SG/(3960*Eff).  ERROR:  The variable "Power" is undefined.  6-Contributor
(To:Ben_Hagler)

Can you show have to do this in MathCad Prime... I just noticed that you might have do this in MathCad and not Prime.  23-Emerald III
(To:Ben_Hagler)

You should not worry about the error message. The variables are numerically undefined. But the symbolic processor doesn' t mind and solves.

If you look carefully you can see that mathcad 11 also complains about undefined variables, one of them is flagged red. So there's no essential difference between Mathcad and Prime in that respect.

Success!

Luc  23-Emerald III
(To:LucMeekes)

If you really cannot live with numerical errors, this should be the way out:

Define your equation similarly to the one in the Prime example; as a function: Success!
Luc  23-Emerald III
(To:Ben_Hagler)

Or, numerically, in Prime: Success!
Luc  6-Contributor
(To:LucMeekes)

I got this to work...and understand it.  Thanks... the root command should work well for all my equations.

I prefer the first method because it is more transparent to a third party.  It shows the equations solved for the unknown.  It also is less confusing by passing a guess.

I have about 40 equations pump related equations in my HP 50G calculator.  I use these equations to solve problems by navigating from equations to equation solving for unknowns.  The variables are passed seamlessly from formula to formula.  This method is quick and dirty but it does not document my work.

What is the best approach for storing many equations in a  MathCad Sheets.

Randomly assemble Pre-Defined equations to a project worksheet to solve problem.

Thanks... Announcements
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