(j3.2006) Question about DIM

Robert Corbett robert.corbett
Tue Jan 12 01:25:06 EST 2016

On 01/11/16 05:49, Bill Long wrote:
> Perhaps a more interesting question is whether this relic is actually used?   I can?t remember ever seeing it, though with only 48 years of Fortran programming experience, I?m a relative newcomer. :)
> If there was any motivation to update DIM, more interesting questions would be
> 1) If X-Y is -0.0, is the result 0.0 or -0.0?
> 2) If X-Y is NaN, what is the result?

I have not only seen DIM used, I have seen a bug report filed against it.  The 
user called the function with integer arguments that overflowed when the 
subtraction was done.  The function result was negative because of the 
overflow.  The user claimed that the Fortran standard required the result to be 

I wrote my first Fortran program for a DEC PDP-8s in the summer of 1967.  I 
understand that that makes me a latecomer to Fortran relative to some on the 

Bob Corbett

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