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| -rw-r--r-- | Doc/ref/ref5.tex | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/Doc/ref/ref5.tex b/Doc/ref/ref5.tex index f554ab4..af1fa19 100644 --- a/Doc/ref/ref5.tex +++ b/Doc/ref/ref5.tex @@ -599,10 +599,20 @@ The power operator has the same semantics as the built-in \function{pow()} function, when called with two arguments: it yields its left argument raised to the power of its right argument. The numeric arguments are first converted to a common type. The result -type is that of the arguments after coercion; if the result is not -expressible in that type (as in raising an integer to a negative -power, or a negative floating point number to a broken power), a -\exception{TypeError} exception is raised. +type is that of the arguments after coercion. + +With mixed operand types, the coercion rules for binary arithmetic +operators apply. For int and long int operands, the result has the +same type as the operands (after coercion) unless the second argument +is negative; in that case, all arguments are converted to float and a +float result is delivered. For example, \code{10**2} returns \code{100}, +but \code{10**-2} returns \code{0.01}. (This last feature was added in +Python 2.2. In Python 2.1 and before, if both arguments were of integer +types and the second argument was negative, an exception was raised). + +Raising \code{0.0} to a negative power results in a +\exception{ZeroDivisionError}. Raising a negative number to a +fractional power results in a \exception{ValueError}. \section{Unary arithmetic operations \label{unary}} |