sympy/sympy — pull request #712 by smichr (2011-11-13 04:42:39+00:00)
Title: evalf: 1->1.0; no expand or conjugate with symbolic expressions

Expanding a Mul or Power makes sense when dealing with numeric
expressions, e.g. (1 + I)**2, but need not be done for symbolic
expressions. The same applies for the use of conjugate to deal
with expressions like 1/(1 + I).

Also, +/-1 were not being processed but they are now. The only
caveat is that the negative 1 on an expression like -x is not
changed to 1.0.