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ptc-50959191-Visitor
1-Visitor
May 9, 2013
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Symbolic differentiation error

  • May 9, 2013
  • 2 replies
  • 2587 views

There may be a Mathcad bug in the attached Mathcad file.

The symbolic partial derivative evaluated with respect to the variable C59 should be zero as the equation can be simplified to not include any C59 terms.

When the differentiate operator is used on the un-simplified equation with respect to C59 a non-zero symbolic derivative results. I'm afraid that this may affect the symbolic results of other equations.

Other than simplifying the equations, is there a workaround to this issue?

Thank you!

Best answer by Werner_E

Its not a bug at all - just tell Mathcad to simplify when you take the derivative of the unsimplified term.

Mathcad will only do very basic simplifications if you just use symbolic evaluation

simplify0.png

so normally you would have to tell Mathcad to simplify the evaluation and probably also how (expand, factor, collect,...)

simplyfy1.png

Nevertheless I would suggest always to simplify expressions whenever possible before doing symbolic operations on them.

2 replies

Werner_E
Werner_E25-Diamond IAnswer
25-Diamond I
May 9, 2013

Its not a bug at all - just tell Mathcad to simplify when you take the derivative of the unsimplified term.

Mathcad will only do very basic simplifications if you just use symbolic evaluation

simplify0.png

so normally you would have to tell Mathcad to simplify the evaluation and probably also how (expand, factor, collect,...)

simplyfy1.png

Nevertheless I would suggest always to simplify expressions whenever possible before doing symbolic operations on them.

ptc-50959191-VisitorAuthor
1-Visitor
May 9, 2013

Thank you for your response!

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