substitute parsing error

[augustinas1]

Trying to substitute products of variables into symbolic expressions can sometimes fail:

julia> @variables x y z
3-element Vector{Num}:
 x
 y
 z

julia> substitute(x*y, x*y => z)
z

julia> substitute(2*x*y, x*y => z) # expect 2z
2x*y

Seems to be some sort of parsing error?

[YingboMa]

substitute doesn't support matching on non-Sym Symbolic. You should use rules.

[erny123]

@YingboMa it doesn't work even when it's all symbolic variables and how would you do this with rules? Rules have the same problem.

here's an example:

@variables a, b, c, d, e, f
test = a*b*c/d
substitute(test, Dict(a*c=>e*f))

Substitute does nothing in this cases.

Using any Symbolics.jl variables with the SymbolicUtils.jl @rules is also a huge mess and not well documented.