## Calculate the Root of a Number [closed]

For someone that has a limited math background can someone tell me what is the most straightforward and accurate way to calculate what the i-root of a float / integer number is?

PS: If someone would care to tag this question properly I would appreciate it, since I have no idea...

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This is not an appropriate question for MathOverflow. Please see mathoverflow.net/faq#whatnot for a description of what kind of question is appropriate and for a list of suggestions of online places where your question will fit better. – Mariano Suárez-Alvarez Dec 29 2009 at 7:39
With a good calculator. – Jonas Meyer Dec 29 2009 at 8:06
I think that the question might be asking for an algorithm to compute roots. There's a good one based on Newton's method and described in this wikipedia page: en.wikipedia.org/wiki/Nth_root_algorithm – José Figueroa-O'Farrill Dec 29 2009 at 8:27
I've retagged it since it is certainly not <code>lo.logic</code>. Assuming I understand the question correctly, <code>algorithms</code> seems to me the closest appropriate tag. – José Figueroa-O'Farrill Dec 29 2009 at 8:30
Alix, the mathematics you are interested in is not clear. Newton's method will rapidly converge to the root, but it won't give you the exact answer. bcroot apparently stops after a certain threshhold or a certain number of iterations that gave you a 3×10^-12% overestimate. Do another iteration of Newton's method and you'll be closer; better, write your own program that gives you as many digits as desired. Perhaps you expect that in the case of perfect integer powers the answers should be exact; for that you will need a different algorithm. I still think you'll do better asking elsewhere. – Jonas Meyer Dec 29 2009 at 11:39