Plots do not appear when executed plot_implicit()

[jmarcellopereira]

Plots do not appear when executed:

p = plot_implicit(Or(Eq(f3(x, y), 0), Eq(f4(x, y), 0)), (x, -5, 5), (y, -5, 5));

Only one plot is shown.

[jverzani]

Hmm, this may be a SymPy bug. I think the following (from https://docs.sympy.org/latest/modules/plotting.html) bypasses any SymPy.jl features, and there is still the issue:

@vars x y
plot_implicit(sympy[:Or](sympy[:Ge](y,x), sympy[:Ge](y,-x)));

If you are using Plots, there are two other alternatives. One is ImplicitEquations, which would be called like:

using ImplicitEquations
IE = ImplicitEquations
f3(x,y) = y - x; f4(x,y) = y + x
plot(IE.Ge((f3, 0) | IE.Ge(f4,0))

If you want to use expressions, this pattern can work:

plot(IE.Ge(lambdify(y-x,[x,y]), 0) | IE.Ge(lambdify(y+x,[x,y]),0))