Calculating nth root in Java using power method

Question

I was trying to get a cubic root in java using Math.pow(n, 1.0/3) but because it divides doubles, it doesn\'t return the exact answer. For example, with 125, this g

Answer 1

The Math.round function will round to the nearest long value that can be stored to a double. You could compare the 2 results to see if the number has an integer cubic root.

double dres = Math.pow(125, 1.0 / 3.0);
double ires = Math.round(dres);
double diff = Math.abs(dres - ires);
if (diff < Math.ulp(10.0)) {
    // has cubic root
}

If that's inadequate you can try implementing this algorithm and stop early if the result doesn't seem to be an integer.