Solving for symbols with large exponents is slow

[Sircular]

The following MWE takes 100% of a CPU core and does not find the solution after a full minute:

from sympy import Symbol
from sympy.solvers import solve

r = Symbol('r')
eq = (1+r)**30 - 1.5
solve(eq, r)

[llucifer97]

hi @Sircular i ran this code i have shared the result.
it ran without a error.

[warnerjon12]

SymPy is a tool, and like all tools, it can only be used well if you know the best way to use it. In your example, it is easy to see how SymPy might solve it, but in the general case it is hard to program intuition. As such, it is up to you as the user to determine how best to express your problem so that SymPy will work the fastest. In this case, I can get the exact answers in under 3 seconds using this code:

r = Symbol('r')
eq = r**30 - Number(3) / 2
print([s.subs(r, 1+r) for s in solve(eq, r)])

[smichr]

Were you wanting all roots or a simple inversion?

>>> [i.subs(y, 30) for i in solve((x+1)**y-1.5,x)]
[0.0136072508934197]

[oscarbenjamin]

Ideally a solution would be found even where there are floats in the input. Perhaps it would be appropriate to return float solutions for float input.