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Re: Matrix operation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg125774] Re: Matrix operation
  • From: Dana DeLouis <dana2010 at me.com>
  • Date: Mon, 2 Apr 2012 04:22:07 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

>    - s2[i, j] = s1[i, j] + 4 * s1[i - 1, j] where i == 4

Hi.  Just another option similar to others:
(Not sure if you meant a negative sign in front, but easy to adjust)

s2 = s1;
r = 4;
s2[[r]] = s2[[r]] + 4*s2[[r - 1]];

= = = = = = = = = =
HTH  :>)
Dana DeLouis
Mac & Math 8
= = = = = = = = = =


On Mar 31, 4:46 am, Andrey Demidov <andrey.demi... at gmail.com> wrote:
> Hi,
> 
> I have a matrix:
> 
> >> s1 = {{0, 4, 3, 6, 1, 0, 0, 30}, {0, 6, 16, 8, 0, 1, 0, 256}, {0, 4, 1,
> 
>     10, 0, 0, 1, 9}, {1, -2, -4, -3, 0, 0, 0, 0}}
> 
> >> MatrixForm[s1]
> 
> Now, I need to get another matrix (s2) where:
> 
>    - s2[i, j] = s1[i, j] where i <> 4
>    - s2[i, j] = s1[i, j] + 4 * s1[i - 1, j] where i == 4
> 
> What is the best way to get s2 ?









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