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ifomenko1-Visitor
1-Visitor
August 15, 2017
Solved

Bug in symbolic integration?

I try to get formula for ellipse area in polar coordinates. I've got it but symbolic result is wrong. I can`t understand why?

Symbolic Area is zero.GIF

One more example with strange behaviour

Symbolic integration bug-2.GIF

 

Werner_E
Werner_EAnswer
25-Diamond I
August 16, 2017

The Mupad version licensed by PTC for Mathcad seems to be very old and also quite limited in functionality (compared to whats possible in Matlab).

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14 replies

LucMeekes23-Emerald V
23-Emerald V
August 16, 2017

No, I'd rather think it's a bug in your formulation of the integral. Why additionally integrate from 0 to 1?

Ellipse.png

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ifomenko1-VisitorAuthor
1-Visitor
August 16, 2017

Symbolic Area is zero (answer).GIF

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LucMeekes23-Emerald V
23-Emerald V
August 16, 2017

Check my attachment (I've attached the file to my first reply), and see where a difference (if any) occurs.

 

Success!
Luc

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Werner_E
Werner_E25-Diamond I
25-Diamond I
August 16, 2017

Before evaluting the definite integral, Mathcads symbolics calculates the indefinite one and I guess that the problem lies here.

The expression MuPad calculates seems not to be valid for the full range of t (or its wrong completely?)

I guess that Lucs MC11 with Maple gives a different result

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ifomenko1-VisitorAuthor
1-Visitor
August 16, 2017

And,so is this Achilles' heel?

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