On Feb 14, 2011, at 3:26 PM, David Van Horn wrote: > On 2/14/11 3:14 PM, Sam Tobin-Hochstadt wrote: >> No, it's not a bug. Since 1e100 is an inexact number, there's >> uncertainty about the minimum of those two numbers, and the result is >> therefore inexact. > > I would've expected min to return a number that is `eq?' to one of its > arguments. > > In other words, what is wrong with this definition of `min'? > > (define (min n1 n2) > (cond [(<= n1 n2) n1] > [else n2]))
What's wrong with this is that, mathematically, since 1e100 is inexact, we're not CERTAIN it's >= 0, so the "proper" answer to (<= n1 n2) is not true but rather almost-certainly-true. (An "inexact Boolean", if you will....) When you define the function as above, the "<=" takes its best guess as to which number is really smaller and pretends that the answer is certain. Stephen Bloch sbl...@adelphi.edu _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
