MathAction #262 Local variables in output

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  - #262 Local variables in output <-- You are here.

In some cases FriCAS introduces special names such as %x0 standing for roots. For example:

fricas

(1) -> eq:=-cos(12*x)+x^2+x^3

$\label{eq1}-{\cos \left({{12}\ x}\right)}+{{x}^{3}}+{{x}^{2}}$

(1)

Type: Expression(Integer)

fricas

zerosOf(eq,x)

$\label{eq2}\begin{array}{@{}l} \displaystyle \left[ \%x 0, \:{\frac{{\sqrt{-{3 \ {{\%x 0}^{2}}}-{2 \ \%x 0}+ 1}}- \%x 0 - 1}{2}}, \: \right. \ \ \displaystyle \left.{\frac{-{\sqrt{-{3 \ {{\%x 0}^{2}}}-{2 \ \%x 0}+ 1}}- \%x 0 - 1}{2}}\right]$

(2)

Type: List(Expression(Integer))

That is OK and we can learn about defining equation like this:

fricas

definingPolynomial %x0

$\label{eq3}-{\cos \left({{12}\ x}\right)}+{{\%x 0}^{3}}+{{\%x 0}^{2}}$

(3)

Type: Expression(Integer)

However, in this case the expression (3) surfaces bug in the solver: the variable x should not appear in the defining polynomial of %x0. In fact, since the equation is not a polynomial in x zerosOf should probably reject it.

Subject: Be Bold !!

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