"Tiago Katcipis" <[EMAIL PROTECTED]> wrote > def newton_divergente(x): > return math.pow(x, 1.0/3.0) > > but when x = -20 it returns this error > > return math.pow(x, 1.0/3.0) > ValueError: math domain error > > but why is that? is it impossible to calculate -20 ^ (1/3) ?
It may be your use of the pow() function: >>> pow(20, 0.3333333) 2.7144173455393048 >>> pow(-20, 0.3333333) Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: negative number cannot be raised to a fractional power >>> -20**0.3333333 -2.7144173455393048 >>> So the exponentiation operator seems happy but pow isn't. Very strange and potentially a bug in pow()? Unless someone knows a reason for it? -- Alan Gauld Author of the Learn to Program web site http://www.freenetpages.co.uk/hp/alan.gauld _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
