On Fri, Dec 21, 2001 at 04:22:42PM -0600, Oleg Galbert wrote:
test n cosx | n==0 = cosx | otherwise = test (n-1) (cosx+cos(cosx))
Functions by default are lazy, i.e. they does not compute the number, but make a note to do it later. In the example you presented, the value of cosx is not needed until the call for "test (n-1) (cosx+cos(cosx))". So, as a result of "test 10000000 0.0" you get a (...+cos(0.0+cos(0.0)))...). That's not surprising it crashes the program.
test1 n cosx | n==0 = cosx | otherwise = cosx `seq` test1 (n-1) (cosx+cos(cosx))
Here, you make sure that cosx is counted up to a number. This function works OK. read http://haskell.org/ghc/docs/latest/set/faster.html
main = print ( test 10000000 0.0 )
Oleg Galbert
Max.