formatter expr add simplify

for expressions like (1+i)*(1-i)

calcpy/formatters.py

@@ -131,8 +131,10 @@ def evalf(expr:sympy.Expr):
                 return factor
             return expand
         return expr
+    expr = expr.simplify()
     types = set(map(type, expr.atoms(sympy.Rational, sympy.Function, sympy.NumberSymbol, ExprWithLimits)))
     types -= {sympy.Integer, sympy.core.numbers.Zero, sympy.core.numbers.One, sympy.core.numbers.NegativeOne}
+    # call evalf only when needed - fractions, functions (e.g. trigonometric), constants (e.g. pi) or limits
     if calcpy.auto_evalf and types:
         return expr.evalf(chop=calcpy.chop, n=15)
     return expr

calcpy/tests/test_formatters.py

@@ -1,9 +1,19 @@
 from sympy.abc import x, y
+from sympy import I as i
+from sympy import Rational
 from IPython.lib.pretty import pretty
+from calcpy.formatters import evalf
 
 def test_unicode_power(ip):
     assert pretty(x**3+2*x**2+3) == 'x³ + 2⋅x² + 3'
     assert pretty(x**-1) == 'x⁻¹'
     assert pretty((x+y)**-1) == '(x + y)⁻¹'
     assert pretty((x+y/5)**-2) == '(x + y/5)**(-2)'
     assert pretty((x/y)**-2) == 'y**2/x**2'
+
+def test_evalf(ip):
+    assert evalf(x**2+2*x+1) == (x+1)**2
+    assert evalf((x+1)**2) == x**2+2*x+1
+    assert evalf((i+1)*(i-1)) == -2
+    assert evalf((i+1)/(i-1)) == -i
+    assert evalf(Rational(1,2)) == 0.5