Re: Input on Linear Algebra: start at zero ! Please!

Nick van Eijndhoven (Nick@fys.ruu.nl)
Fri, 14 Nov 1997 16:32:54 +0100 (MET)

*** Fons Rademakers wrote :
>
> Just a clarification.
>
> Matrices use internally, for efficiency reasons, column
> wise storage. This however is completely hidden from the
> user. The element m(i,j) is the element at the i-th row
> and j-th column (like in math and C/C++). The issue is: is,
> by default, the first element m(1,1) or m(0,0). Currently
> I've implemented (0,0) as first element. For example:
>
> TMatrix m1(4,20); // m1(0,0) ... m1(3,19), same as
> TMatrix m2(0,3,0,19); // m2(0,0) ... m2(3,19)
> TMatrix m3(1,4,1,20; // m3(1,1) ... m3(4,20)
>
> It could be:
>
> TMatrix m4(4,20); // m4(1,1) ... m4(4,20)
>
> I've seen a number of packages using 1 as lowerbound
> and a number of packages using 0.
>
> Let me know your preference.
>
> -- Fons.
>
Hi Fons,
This is exactly the way I used it for the ALICE stuff, and again
I prefer the m(1,1) to be the first element in order to be in line
with math books, formulas and common sense.

Cheers,
Nick.

*----------------------------------------------------------------------*
Dr. Nick van Eijndhoven Department of Subatomic Physics
email : nick@fys.ruu.nl Utrecht University / NIKHEF
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