Index: Doc/library/functions.rst
===================================================================
--- Doc/library/functions.rst	(revision 84374)
+++ Doc/library/functions.rst	(working copy)
@@ -192,13 +192,21 @@
 .. function:: complex([real[, imag]])
 
    Create a complex number with the value *real* + *imag*\*j or convert a string or
-   number to a complex number.  If the first parameter is a string, it will be
-   interpreted as a complex number and the function must be called without a second
-   parameter.  The second parameter can never be a string. Each argument may be any
-   numeric type (including complex). If *imag* is omitted, it defaults to zero and
-   the function serves as a numeric conversion function like :func:`int`,
-   :func:`long` and :func:`float`.  If both arguments are omitted, returns ``0j``.
+   number to a complex number. 
+   
+   If the first parameter is a string, it will be interpreted as a complex number
+   and the function must be called without a second parameter.  The string
+   parameter must not contain any whitespace around the central operator (or 
+   else :exc:`ValueError` will be raised).
+   ``1+2j`` is fine where ``1 + 2j`` or other variants with whitespace between
+   the real and imaginary numbers is not. The second parameter can never be a
+   string. 
 
+   Each argument may be any numeric type (including complex). If *imag* is
+   omitted, it defaults to zero and the function serves as a numeric conversion
+   function like :func:`int`, :func:`long` and :func:`float`.  If both arguments
+   are omitted, returns ``0j``.
+
    The complex type is described in :ref:`typesnumeric`.