Re: Powers of 5

Josh wrote:
Rick Decker wrote:
....
Powers of 5 of the form 2^k (i.e. 5^(2^k)) can be computed quickly
by successive squaring. For example,
....
That's perfect. I wish I had thought of that. I rewrote the function
in Python for the sake of being concise, but now the function takes k
rather than 2^k as its argument. So I guess I haven't really answered
the question.

def power(k):
if (k <= 1):
return 5
else:
return power(k-1)**2
....
At any rate, I digress. I'm just missing how to get the function to
take 2^k as its argument. If you don't mind helping a little more, I
would be grateful.
....

You merely replaced "return (5 * power(n-1))" with
"return power(k-1)**2". Instead, make the function
split three ways -
if n <= 1 return 5,
else if n is even return the square of something,
else return power(n-1)*5.

[Helpful example: x^14 = (x^7)^2.]
-jiw
.

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