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-MFra-21-Topaz II
21-Topaz II
June 8, 2022
Solved

Different results in calculating the sum of a given infinite series.

  • June 8, 2022
  • 2 replies
  • 1539 views

Hello everyone!
Why does the symbolic processor give me different results in calculating the sum of the infinite series shown in the photo? Does Prime produce the same results?

Conundrum.jpg

Best answer by Werner_E

Found something interesting:

Werner_E_0-1654726305412.png

So this may be a quite clumsy workaround

Werner_E_1-1654726340036.png

But it only works if the variable a is not defined. Otherwise the error pops up again:

Werner_E_2-1654726420822.png

But the best "workaround" if one already is aware of this bug, sure is to put the factor outside the parenthesis

Werner_E_0-1654881081034.png

Its a strange bug, indeed!

 

 

2 replies

L
LucMeekes23-Emerald IV
23-Emerald IV
June 8, 2022

This is Mathcad 11 (with Maple as symbolic engine). It knows Catalan symbolically:

LucMeekes_0-1654707473978.png

so

LucMeekes_1-1654707492198.png

It doesn't recognise your series to be related to Catalan:

LucMeekes_2-1654707545880.png

but at least, it's consistent in it answers/results.

 

Prime 8 has the 'new symbolic machine' and produces:

LucMeekes_3-1654707627882.png

LucMeekes_4-1654707645626.png

LucMeekes_5-1654707671408.png

 

and

LucMeekes_6-1654707690343.png

which is also consistent. Prime 7 is the same.

I suppose that Prime 1...5 will produce the same as Mathcad 15, due to MuPad. Prime 6 gives the choice between MuPad and the new symbolic machine.

 

Success!
Luc

 

    W
    Werner_E25-Diamond I
    25-Diamond I
    June 8, 2022

    Its definitely a bug in muPad but as neither MC15 nor Prime6- are supported by PTC anymore, I guess you are out of luck hoping for a fix.

    The symbolic is ignoring the factor if its placed within the squared parenthesis.

    Werner_E_0-1654725789654.png

    You get the result which matches the result Luc had shown with P8 if you use the limit

    Werner_E_1-1654725869161.png

    Adding a "simplify" or a "simplify,max" sometimes returned the very same result and sometimes ended in an endless calculation which I had to cancel.

    As Luc already guessed we get the very same erroneous results with the legacy symbolic in Prime 6 and switching to the new one delivers the same results Luc had shown for P8.

     

    W
    Werner_E25-Diamond IAnswer
    25-Diamond I
    June 8, 2022

    Found something interesting:

    Werner_E_0-1654726305412.png

    So this may be a quite clumsy workaround

    Werner_E_1-1654726340036.png

    But it only works if the variable a is not defined. Otherwise the error pops up again:

    Werner_E_2-1654726420822.png

    But the best "workaround" if one already is aware of this bug, sure is to put the factor outside the parenthesis

    Werner_E_0-1654881081034.png

    Its a strange bug, indeed!

     

     

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