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Liv7-Bedrock
7-Bedrock
February 13, 2017
Solved

polyroots with two arguments

  • February 13, 2017
  • 1 reply
  • 4204 views

Hello everybody !

I am just curious if the first argument of polyroots has some (useful) meaning (see highlighted region in attached), since subsequent calculations in the worksheet work fine.

The equation originates from the simple DE :  dT(z)/dz = [deltaH/cpm(T)] * dgCO(z)/dz , with the initial conditions : T(0) = T0 and gCO(0) = some value.

I suppose that's something coming from the cuisine of muPad symbolic engine...

Note that value displayed as first argument at polyroots may change on re-opening the file.

Best regards, Liv.

Best answer by Werner_E

Interesting!

The first parameter which is added by symbolic evaluation changes also when the expression is evaluated several times but it does no change when the sheet or expression is recalculated.

Basically polyroots is a function which should only be evaluated numerically.

I have no idea what the symbolics thinks it is.

Even in Mupad its a numerical function only and the syntax is different from the one used in Mathcad

-> Numerical roots of a univariate polynomial - MuPAD - MathWorks Deutschland

The expression produced by the symbolic eval cannot be evaluated numerically and the error message is remarkable

As far as I am aware accepts polyroot only 1 argument (the coeff vector), not 2, and as far as I see in the picture its applied to just 2 arguments and not to 4.

1 reply

W
Werner_E25-Diamond IAnswer
25-Diamond I
February 13, 2017

Interesting!

The first parameter which is added by symbolic evaluation changes also when the expression is evaluated several times but it does no change when the sheet or expression is recalculated.

Basically polyroots is a function which should only be evaluated numerically.

I have no idea what the symbolics thinks it is.

Even in Mupad its a numerical function only and the syntax is different from the one used in Mathcad

-> Numerical roots of a univariate polynomial - MuPAD - MathWorks Deutschland

The expression produced by the symbolic eval cannot be evaluated numerically and the error message is remarkable

As far as I am aware accepts polyroot only 1 argument (the coeff vector), not 2, and as far as I see in the picture its applied to just 2 arguments and not to 4.

L
Liv7-BedrockAuthor
7-Bedrock
February 13, 2017

"remarkable" : agree...

One can get also something like :

polyr.jpg

W
Werner_E25-Diamond I
25-Diamond I
February 13, 2017

Strange!

"solvecb" seems to be an internal command. I don't know any  CAS this command could stem from.

It looks like it has nothing to do with the symbolics. Its implemented in mathdllr.dll and is referenced in mpl\mcdtranslator.mpl and also in prolog\compute.prolog.

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