[Tutor] iscube function

Terry Carroll carroll at tjc.com
Wed Apr 11 02:11:03 CEST 2007

On Tue, 10 Apr 2007, Robert William Hanks wrote:

> how is the best way to find out if a number is a perfect cube in python?
>   i am working if integer numbers only. i am asking because
>  pow(1728, 1.0/3.0) --> 11.999999999999998

def iscube(n):
    cubed_root = n**(1/3.0)
    if round(cubed_root)**3 == n:
        return True
        return False

if __name__ == "__main__":
    rootlim = 20
    calculated_cubes = [n**3 for n in range(1,rootlim+1)]
    found_cubes = [n for n in range(1, rootlim**3+1) if iscube(n)]
    if found_cubes == calculated_cubes:
        print "Hey, it worked!"
        print "Oops."
        missed_cubes = [n for n in calculated_cubes if n not in found_cubes]
        wrong_cubes = [n for n in found_cubes if n not in calculated_cubes]
        print "missed cubes:", missed_cubes
        print "wrong cubes:", wrong_cubes


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