RecursionError for unevluated expression in latex

[proy87]

latex(Mul(Pow(Integer(2), Integer(-1), evaluate=False), Add(Integer(1), i, evaluate=False), Add(Integer(1), Pow(i, Integer(-8), evaluate=False), evaluate=False), evaluate=False))

[oscarbenjamin]

I presume that i here is sympy.I

[proy87]

@oscarbenjamin, yes.

[KuldeepBorkar]

@oscarbenjamin, @proy87
Specifically we can say error comes here
z = Pow(I, Integer(-8), evaluate=False)

[KuldeepBorkar]

Yeah it's getting error trying to do this -1**(-8) when evaluate=False.
Say, for any negative number except -1

[oscarbenjamin]

The error is here:

sympy/sympy/printing/latex.py

Lines 567 to 572 in 7dbc2f4

	numer, denom = fraction(expr, exact=True)
	if denom is S.One and Pow(1, -1, evaluate=False) not in expr.args:
	# use the original expression here, since fraction() may have
	# altered it when producing numer and denom
	tex += convert(expr)

The problem is that in this case:

In [5]: z
Out[5]: 
1 
──
 8
ⅈ 

In [6]: fraction(z, exact=True)
Out[6]: (1, 1)

When we call convert with expr we get right back here again. The problem with fraction can be fixed with:

diff --git a/sympy/simplify/radsimp.py b/sympy/simplify/radsimp.py
index 91078be..6d18499 100644
--- a/sympy/simplify/radsimp.py
+++ b/sympy/simplify/radsimp.py
@@ -1089,11 +1089,11 @@ def fraction(expr, exact=False):
                     denom.append(b)
                 elif exact:
                     if ex.is_constant():
-                        denom.append(Pow(b, -ex))
+                        denom.append(Pow(b, -ex, evaluate=not exact))
                     else:
                         numer.append(term)
                 else:
-                    denom.append(Pow(b, -ex))
+                    denom.append(Pow(b, -ex, evaluate=not exact))
             elif ex.is_positive:
                 numer.append(term)
             elif not exact and ex.is_Mul:

[KuldeepBorkar]

Thanks @oscarbenjamin I will make the changes quick.