Hi Stephen
On 2014-05-29, Stephen Kauffman <[email protected]> wrote:
> Specifically I have a polynomial such as mypoly = X*Y + 1 in
> BooleanPoynomialRing() and str(mypoly) converts it to the string 'X*Y + 1'
> then I do some stuff with re pattern matching to construct the string '1 -
> x*y' which I now want to convert to a polynomial in 'x' and 'y' in QQ. Are
> there any built in functions or methods to do that?
Generally, if you have an algebraic structure Y (often called "parent") in
Sage, and have some element x of some other algebraic structure x, then
Y(x) tries to convert x into an element of Y. The same holds for
conversion of a string.
Note, however, that a conversion is not necessarily making mathematical
sense, if the structures X and Y are too different (i.e., there may be
no homomorphism from X to Y). So, use conversions only if you know what
you are doing.
What you describe would be as follows:
sage: P.<x,y> = BooleanPolynomialRing()
sage: mypoly = x*y+1
sage: R = QQ['x','y']
sage: R(mypoly)
x*y + 1
sage: R('1-x*y') # replacing + by - in str(mypoly)
x*y - 1
Best regards,
Simon
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