Re: gnuplot cvs source bug

[Robert H. <en...@no...>]

On Fri, 2005-09-23 at 15:48 +0200, Hans-Bernhard Broeker wrote:

> Yes, and I will until the day the first DIWM (for "do-what-I-mean") 
> interfaced computer becomes available --- it's been elusive for so long 
> that I seriously doubt it will ever happen, though.

Until then we have the "principle of least surprise" - in other words a
computer can be made to "DWIM" as much of the time as possible by doing
what you would expect most likely it to do. Thus in the context of a
scientific plotting package that primarily plots continuous functions
and arbitrary discrete data, the mathematical (and human) definition of
division would be expected.

> > Can you actually think of a real-life case where integer maths is the
> > "correct" way of doing a calculation *and* explicitly using the int()
> > function would not be appropriate?
> 
> Yes.  It's quite obvious, too: integer maths has applications where 
> floats simply don't apply.  gnuplot has binary operators like '%', '|', 
> '&' and '^' which are applicable only to integers.

Yes, but we are talking about a situation where floats *do* apply.
Surely it is more logical to treat numbers as floats *unless* they are
used in a context where only integers apply. For any ambiguous case
(division and exponentiation), anybody who wants the integer math
*knows* they want it and can use int()

Other counter-intuitive behaviour:

gnuplot> print 1/(5**1)
0
gnuplot> print (5**-1) 
0.2

gnuplot> x=1000000000000000000                                 
gnuplot> print x              
2147483647
gnuplot> x=1000000000000000000.0
gnuplot> print x                
1e+18
gnuplot> x=1*10**18
gnuplot> print x
-1486618624


-- 
Robert Hart <en...@no...>
University of Nottingham


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