MathCad 13 vs MathCad 14 - a problem with a "solve" function

[DN_11123007]

Hello everyone

I worked on MathCad 13 for years, but recently switched to MathCad 14.

Generally, both versions are very similar, but it turned out that I have a problem - MathCad 14 is not able to solve some equations using the "solve" function, which version 13 solved. After a few seconds of "struggle", an error message appears, as in the attached graphic.

In turn, in cases where version 14 solves equations created in version 13, it does it very slowly - in version 13 they were solved immediately after opening the file, and in version 14 you have to wait a long time, even about 10 seconds.

What is the problem and how to solve it?

I would like to mention that I cannot return to version 13, which I would like to do.

Thanks

[LucMeekes]

The symbolic processor in Mathcad 13 is Maple. In Mathcad 14 it is Mupad. There is quite some difference between these two in terms of what they can solve and how the output is presented.

Note that neither of the two versions is supported anymore.

Success!

Luc

[DN_11123007]

So, does it mean that version 14 is worse than version 13, to put it simply?

In my case the calculations take much longer or fail at all...

And the question from my previous post remains - how to solve that specific problem, concerning this equation shown before?

[AlfredFlaßhaar]

Please send a file *.mcd or *.xmcd instead of *.jpg.

[DN_11123007]

Here it is.

[AlfredFlaßhaar]

Even under the obviously necessary condition phi >0, no convergence occurs. Therefore, in MC14, I was left with only the attached solution.

[Werner_E]

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Therefore, in MC14, I was left with only the attached solution.

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I can spot no solution value in your sheet.

We would have to compare f(phi( with phi to find the moist suitable values:

But we could let Mathcad do this job and  use the "Lookup" function from the Data Analysis Extension Pack to find the values closest to the solution (within the precision set by your approach):

Nonetheless I would suggest to rather use Mathcads numeric facilities as explained in detail here: https://community.ptc.com/t5/Mathcad/MathCad-13-vs-MathCad-14-a-problem-with-a-quot-solve-quot/m-p/955219/highlight/true#M212410

[Werner_E · Accepted solution]

As Luc already wrote there was a change in the symbolic processor from Mathcad 13 to Mathcad 14.

And while I would say that MC14 is an improvment over MC13, this sure does not apply to symbolic operations. Maple as symbolic engine sure was the best engine Mathcad ever had and the successors (muPad since Mathcad 14 and FriCas/Axiom  since Prime 6) are clearly inferior to it.

Concerning the equation you try to solve we can say:

1) The symbolics seems to was improved over time. With the last version of Mathcad 15 (actually just a further maintenance release of MC14) I get

2) After you finally posted your worksheet it could be seen that all other variables in your equation are numerically defined - that means that you are just looking for a numeric solution, not a symbolic one! So there is no reason for using the symbolic "solve" command anyway.

You can use one of Mathcads numeric solvers. These basically are the "root" function (can be used in two ways) or a solve block with "find":

Mathcad 15 sheet attached, You should have no problems opening it with MC14.
The symbolic "solve" possibly still will fail in your version, but I expect that the numeric methods will work OK.

[vnamboodheri]

Hello @DN_11123007, 

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[DN_11123007]

Thanks guys for all the answers.