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13-Aquamarine
April 11, 2018
Question

How to force Mupad

  • April 11, 2018
  • 10 replies
  • 4218 views

First I want to apologize as I did send the same message 30 minutes ago but as I do not see it in the message list I am unsure whether it went through.

I would like to solve this equation (a*b+c*x^d)/(b+x^d)=y for x. In mathematica this went smoothly but not with Mupad (see worksheet). Could one of the more proficient Mupad users show me how I can force Mupad in giving me the same answer as mathematica?

10 replies

23-Emerald IV
April 11, 2018

Mupad? This forum is on Mathcad and Prime!

 

Anyway. It might help if you tell the symbolic processor what type of variables a...d and y are: If they're positive, and/or real (rather than complex).

 

Success!
Luc

FDS13-AquamarineAuthor
13-Aquamarine
April 11, 2018

Sorry Luc, I am using Mupad in Mathcad 15 (should have mentioned that).

23-Emerald IV
April 11, 2018

No problem.

This is what Mathcad 11 with the Maple symbolic engine produces:

LM_20180411_Symbolic.png

Success!
Luc

21-Topaz II
April 11, 2018

Hi FDS,

FDS answer.jpg

25-Diamond I
April 11, 2018

The following study, using a simplified expression, may give you an idea of how muPad ticks. On contrary to Maple it defaults to domain complex and like the symbolics in older versions of Mathcad the assume modifier is not always achieving the desired effect.

Mupad seems to consider much more special cases in its calculations, it "knows" that powers are not defined in real domain for every combination of base and exponent, etc. and while this may be correct from a mathematical point of view it can be annoying in everyday use.

Maybe the problem is, that MuPad first was developed by university mathematicians. maybe the problem is, that Mathcad and Prime are using a very old and limited version of muPad. As muPad now is owned by Mathworks, owners of MatLab and a competitor of PTC  (really? can we still say that Mathcad Prime is a competitor of MatLab?) chances are low that symbolics in Prime will be enhanced in the near future.

Bild.png

 

25-Diamond I
April 11, 2018

This was as  closest as I could come with your equation:

Bild2.png

21-Topaz II
April 12, 2018

FDS answer 1.jpg

FDS13-AquamarineAuthor
13-Aquamarine
April 12, 2018

Thank you all for your help! All explanations were much appreciated