sage.functions: Fix up replacement of is_{Real,Complex}[Double]Field

Author: Matthias Koeppe

src/sage/functions/orthogonal_polys.py

@@ -671,7 +671,7 @@ def _evalf_(self, n, x, **kwds):
         except KeyError:
             real_parent = parent(x)
 
-            if not isinstance(real_parent, sage.rings.abc.RealField) and not isinstance(real_parent, sage.rings.abc.ComplexField):
+            if not isinstance(real_parent, (sage.rings.abc.RealField, sage.rings.abc.ComplexField)):
                 # parent is not a real or complex field: figure out a good parent
                 if x in RR:
                     x = RR(x)
@@ -680,7 +680,7 @@ def _evalf_(self, n, x, **kwds):
                     x = CC(x)
                     real_parent = CC
 
-        if not isinstance(real_parent, sage.rings.abc.RealField) and not isinstance(real_parent, sage.rings.abc.ComplexField):
+        if not isinstance(real_parent, (sage.rings.abc.RealField, sage.rings.abc.ComplexField)):
             raise TypeError("cannot evaluate chebyshev_T with parent {}".format(real_parent))
 
         from sage.libs.mpmath.all import call as mpcall
@@ -1030,7 +1030,7 @@ def _evalf_(self, n, x, **kwds):
         except KeyError:
             real_parent = parent(x)
 
-            if not isinstance(real_parent, sage.rings.abc.RealField) and not isinstance(real_parent, sage.rings.abc.ComplexField):
+            if not isinstance(real_parent, (sage.rings.abc.RealField, sage.rings.abc.ComplexField)):
                 # parent is not a real or complex field: figure out a good parent
                 if x in RR:
                     x = RR(x)
@@ -1039,7 +1039,7 @@ def _evalf_(self, n, x, **kwds):
                     x = CC(x)
                     real_parent = CC
 
-        if not isinstance(real_parent, sage.rings.abc.RealField) and not isinstance(real_parent, sage.rings.abc.ComplexField):
+        if not isinstance(real_parent, (sage.rings.abc.RealField, sage.rings.abc.ComplexField)):
             raise TypeError("cannot evaluate chebyshev_U with parent {}".format(real_parent))
 
         from sage.libs.mpmath.all import call as mpcall

src/sage/functions/special.py

@@ -159,7 +159,6 @@
 # ****************************************************************************
 
 from sage.rings.integer import Integer
-from sage.rings.complex_mpfr import ComplexField
 from sage.misc.latex import latex
 from sage.rings.all import ZZ
 from sage.symbolic.constants import pi
@@ -362,10 +361,9 @@ def elliptic_j(z, prec=53):
         sage: (-elliptic_j(tau, 100).real().round())^(1/3)
         640320
     """
-
     CC = z.parent()
-    from sage.rings.complex_mpfr import is_ComplexField
     if not isinstance(CC, sage.rings.abc.ComplexField):
+        from sage.rings.complex_mpfr import ComplexField
         CC = ComplexField(prec)
         try:
             z = CC(z)