bug in simplify_fractions?

[jmsull]

Not sure this is exactly the place for this, but I am finding a problem with simplify_fractions.

In particular, using simplify_fractions on a simple example gives the wrong answer (in v1.7.0):

using Symbolics
@variables x y
z = 1 + (1 - x)*y^2 / (2*(1 - x))
simplify_fractions(z)

the above returns 1//0, but should return 1 + 1//2 y^2.

Maybe this is helpful for finding the issue, but there is no problem if I drop the 2 in the denominator (or the 1 + at the front, or use y instead of y^2, or use x instead of 1-x).

This may be related to the most recent comment in JuliaSymbolics/SymbolicUtils.jl#380?

[shashi]

Seems to be from DynamicPolynomials...

(ns[i]).p = -xy² + y² - 2x + 2
(ds[j]).p = -2x + 2
gcd((ns[i]).p, (ds[j]).p) = -xy² + y² - 2x + 2

cc @blegat

[shashi]

Fixed by DynamicPolynomials.jl v0.4.2

[jmsull]

Great - thank you for tracking this down!