stack overflow on recursive function haskell

Question

Here is one implementation of power function in Haskell. But I have stack overflow error. No idea how to fix

power''::Integer->Integer->Integer
power'' _ 0=1
power'' 1 _=1
power'' n k
    |even k = power'' (n*n)  (k `div` 2)
    |otherwise = n * power'' n k-1

Ingo · Accepted Answer · 2013-11-22 11:11:43Z

5

|otherwise = n * power'' n k-1

this is

|otherwise = (n * power'' n k)-1

and hence you recurse with the same arguments forever.

answered Nov 22, 2013 at 11:11

Ingo

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1 Comment

user1876128 Over a year ago

well I have to |otherwise = n * power'' n (k-1)

user1876128 · Accepted Answer · 2013-11-22 11:16:24Z

0

--Found my problem

 |otherwise = n * power'' n (k-1)

answered Nov 22, 2013 at 11:16

user1876128

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