# [racket] Multiplying by 0

On 2/14/11 3:44 PM, Stephen Bloch wrote:
>*
*>* 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.
*
Then what is the correct definition?
David