Re: User selectable lower array bound?

[bennetsc(at)NOSPAMucs.orst.edu]

In article <3B6F037D.B17A6287@astro.cornell.edu>,
JD Smith  <jdsmith@astro.cornell.edu> wrote:
>Paul van Delst wrote:
>> 
>> "Pavel A. Romashkin" wrote:
>> >
>> > Craig Markwardt wrote:
>> > >
>> > > Well, as grumpy as I have been in the past about IDL
>wishes, this is
>> > > one thing I do not want to have in IDL now!
>> >
>> > I am with you Craig. Besides, for the purists of array
>indexing, I think
>> > it is unfair to dasignate a *lower* array bounds. We don't
>designate the
>> > *upper* one.
>> 
>> In the context of initially declaring an array in IDL, sure you do:
>> 
>> x = fltarr(10)
>> 
>> declares the upper bound as 9. We also designate a lower
>bound: 0. The difference between
>> the two is that I can change the former.
>> 
     So how about if {flt,dbl,complex,int,lon,dcomplex,byt,str}arr
and make_array could accept both the form shown above and this form:

	y = fltarr(-5:10)

which would declare the lower bound as -5 and the upper bound as 9,
giving a total of 16 elements, including the zero element?  This
isn't quite as nice as PL/1's method because of the zero element,
but it would be usable and wouldn't break any existing code.  Future
programs would have to take into consideration that

	y = fltarr(-5:-1)

would have a lower bound of -5 and an upper bound of -1, giving
a total of only 5 elements due to the lack of a zero element.  PL/1's
syntax avoided this problem by having the lower bound default to 1
if not coded, but I think I could live with it as long as I were
aware of it.


                                  Scott Bennett, Comm. ASMELG, CFIAG
                                  College of Oceanic and Atmospheric
					Sciences
                                  Oregon State University
                                  Corvallis, Oregon 97331
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