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

From: Nick van Eijndhoven (Nick@fys.ruu.nl)
Date: Fri Nov 14 1997 - 16:32:54 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.

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 Dr. Nick van Eijndhoven                Department of Subatomic Physics
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