On Monday 10 November 2008, Nasser Abbasi wrote:
> Hello;
>
> I was just browsing something to learn about sage, and noticed this on
> this web site
> http://wiki.sagemath.org/sage_mathematica
>
> where it says:
>
> "sage: [f(i) for i in range(1, 11)]
> [g(1), g(2), g(3), g(4), g(5), g(6), g(7), g(8), g(9), g(10)]
>
> (note that the endpoint of the range is not included). "
>
> The above struck me as something that would be confusing and will lead
> to many programming errors. I do not program in Python and played
> with sage very little. But it seems (to me) strange that when one
> write range(i,j) that the sequence will stop at j-1.
>
> Do other who worked with sage more not find this is a bit odd?
This is a standard Python feature. Moreover, it is pretty standard in CS to
have constructs like this, because "we" tend to count from zero: many people
write C (or Java or ....) loops like this:
for(i=0; i<n; i++) {
C[i] = A[i] + B[i];
}
This loops n times but from 0 to n-1. Same goes for range(n). Changing this
convention would break many many packages.
If you really want [1..20] then you can write that:
sage: [1..20]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
Note however, that this is NOT valid Python and ONLY works on the Sage command
prompt and in the notebook. It will not work as library code.
Cheers,
Martin
--
name: Martin Albrecht
_pgp: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x8EF0DC99
_www: http://www.informatik.uni-bremen.de/~malb
_jab: [EMAIL PROTECTED]
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