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ptc-46004791-Visitor
1-Visitor
June 13, 2012
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Mathcad Unit Syntax Problem

  • June 13, 2012
  • 1 reply
  • 2199 views

Good Evening All,

I'm brand new to Mathcad and am having difficulty getting my head around the units synatx.

Please see attatched calculation which is fairly simple.

In this instance my calculation includes emhirical formulae - so to keep things simple I have decided not to specify any units.

However the solve block will not return any results because the 'units are not compatible'. But no units have been used!

Any ideas??? Ive spent an hour trying to figure it out now I finally give in!

Many thanks in advance.

Best answer by nas0k

It appears that "h" has units of kg*m^2/s. Redefining will eliminate the units (call it h1 for example), but then you need a guess value. Then the solver cannot find a solution, but at least the units error is gone.

You are asking to solve for TA yet TA is defined as 12 above the solve block. Also, RC =delta x / kA, is that correct? I would have guessed kC.

Hopefully further (better) help will follow.

Norm

1 reply

N
nas0k1-VisitorAnswer
1-Visitor
June 14, 2012

It appears that "h" has units of kg*m^2/s. Redefining will eliminate the units (call it h1 for example), but then you need a guess value. Then the solver cannot find a solution, but at least the units error is gone.

You are asking to solve for TA yet TA is defined as 12 above the solve block. Also, RC =delta x / kA, is that correct? I would have guessed kC.

Hopefully further (better) help will follow.

Norm

P
ptc-46004791-VisitorAuthor
1-Visitor
June 14, 2012

Hi Norm,

This is what I get for working late at night!

I forgot the guess value for h. I never meant to ask for TA. And your right - RC = delta x / kC.

Problem solved. Many thanks.

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