[clean-list] IEEE floating point and Clean

[Siegfried Gonzi]

 Still under impression from the last day (I do not have got a
televison but after turning on the radio I have been believing the
3 world war had started) I post the following:

Currently, I read Kahan's article "How Java's floating point hurts
everone everywhere":

http://www.cs.berkeley.edu/~wkahan/


But Kahan is playing close to his chest and I cannot really figure out
what he means when he writes that Java has no possibility to handle
exceptions.

I also cannot post my question to a Java discussion group (and they are
astoundingly numerous), because they would not honor the following
Clean code in order to emphasize what bothers me.

Maybe there is a Clean user who has got a basic understanding of
Java's numerics.

- In Clean (on a Macintosh and Sun):

Start = 0.0/0.0                         delivers NAN(000)
Start = 1.0/0.0                         delivers INF
Start = 1.0/(-0.0)                      delivers -INF
Start = 0.0/(1.0/0.0)           	delivers 0
Start = 0.0/(1.0/(-0.0))        	delivers -0

Question 1:

What does Java deliver here?


- In Clean (on a Macintosh and Sun):

Start = [(1.0/toReal(x)) \\ x <- [2,1,0,0,1,2]] 


delivers [0.5,1,INF,INF,1,0.5]

Question 2:

What will Java spy out here (under the assumption that the 
implemented Java function does the same as Clean his
list comprehension)?


- In Clean (on a Macintosh and Sun):

Start =  [1.0/toReal(y) \\ y <-  [1.0/toReal(x) \\ x <- [2,1,0,0,1,2]] ]


delivers [2,1,0,0,1,2]

Question 3:

How will Java do here?


- In Clean (on a Macintosh and Sun):

exception =[check(1.0/toReal(x)) \\ x <- [2,1,0,0,1,2]] 
where
    check y
       | y == infinity = abort("infinity reached")
       = 1.0
       where
         infinity = 1.0/0.0
                
Start = exception


delivers [1,1,infinity reached

Question 4:

What about Java here?


Are my Clean examples some sort of "exception handling"? I cannot prove
it with Java, 
because I do not have installed a Java development kit on any of my 
platforms.


S. Gonzi