smichr/sympy — comment on commit cc64d7975bc5bbca02d7be8a0abea0416e86fab0
File: sympy/solvers/solvers.py line 290
By smichr:

> Another difference is that evalf() does nothing for coefficients of +/- 1.

I'm not sure that an explicit coefficient should be put in. This is
how my evalf branch behaves:

>>> (-x).n()
-x
>>> (-2*x).n()
-2.0*x
>>> (-x-1).n()
-x - 1.0

The only thing that a custom routine might be needed for is to not
float Rational exponents or to float Integer exponents:

>>> root(x,2).n()
x**0.5
>>> (x**2).n()
x**2