>>> erf(1.0/sqrt(2.0)) # portion of normal distribution within 1 standard deviation
0.682689492137086
-:func:`~math.gamma` is a continuous extension of the factorial function. See
-http://en.wikipedia.org/wiki/Gamma_function for details. Because the function
-is related to factorials, it grows large even for small values of *x*, so there
-is also a :func:`~math.lgamma` for computing the natural logarithm of the gamma
-function:
+The :func:`~math.gamma` function is a continuous extension of the factorial
+function. See http://en.wikipedia.org/wiki/Gamma_function for details. Because
+the function is related to factorials, it grows large even for small values of
+*x*, so there is also a :func:`~math.lgamma` function for computing the natural
+logarithm of the gamma function:
>>> gamma(7.0) # six factorial
720.0