radicalSolve mixup

[leh...@bayou.uni-linz.ac.at]

Hello

what is going on here?

***********************************************************
(1) -> radicalSolve([x^2+2*y=2])

+--------+ +--------+
(1) [[y= \|- 2y + 2 ],[y= - \|- 2y + 2 ]]
Type: List(List(Equation(Expression(Integer))))
***********************************************************

regards,
Franz

[Ralf Hemmecke]

Use
radicalSolve([x^2+2*y=2],[x])
instead.

Trying to explain...

Look at

http://github.com/hemmecke/fricas-svn/blob/master/src/algebra/solverad.spad.pamphlet

You'll find...

radicalSolve : (L EQ RF,L SY) -> L L EQ RE
++ radicalSolve(leq,lvar) finds the solutions expressed in terms of
++ radicals of the system of equations of rational functions leq
++ with respect to the list of symbols lvar.
radicalSolve : L EQ RF -> L L EQ RE
++ radicalSolve(leq) finds the solutions expressed in terms of
++ radicals of the system of equations of rational functions leq
++ with respect to the unique symbol x appearing in leq.

Seems that your input is interpreted as a rational function in x.

Now try

(2) -> radicalSolve(x^2+2*y=2)

>> Error detected within library code:
too many variables

Well, seems that this function is a pickier about its input.

Anyway, there clearly is a bug here. I would even claim that the
documentation is buggy. Or does somebody understand what it is trying to
say? For example, what output should I expect from

(3) -> radicalSolve([x^2+2*y=2],[x,y])

? This?

2
- x + 2
(3) [[x= --------]]
2
Type: List(List(Equation(Expression(Integer))))

Ralf