# [R] Problems dealing with matrices

halim10-fes halim10-fes at sust.edu
Sun Nov 24 06:12:33 CET 2013

Please apologize me! Earlier I've sent a message erroneously. Following is the
original problem for which I'm seeking help. Extremely sorry...

Hi Arun,

Thank you very much for your response. Sorry, if I couldn't explain clearly. I
think, I should restate the problem to get exactly what I want. Here it goes:

I have 2 matrices and 1 vector, namely,

dcmat<-matrix(c(0.13,0.61,0.25,0.00,0.00,0.00,0.52,0.37,0.09,0.00,0.00,0.00,
0.58,0.30,0.11,0.00,0.00,0.00,0.46,0.22,0.00,0.00,0.00,0.00,
0.09),nrow=5,ncol=5)

volmat<-matrix(c(100,0,0,0,0),nrow=5,ncol=1)

volinp<-c(1:40)

What I essentially want to do is to multiply 'dcmat' with 'volmat' and dump
the output in a new matrix 'vol'. But before that, in the first step, I want
to add volinp[1] with volmat[1,1]. So, the first column of the output matrix
'vol' matrix will be:

[,1]
[1,]   13.13
[2,]   61.61
[3,]   25.25
[4,]    0.00
[5,]    0.00

In the 2nd step, I want to replace 'volmat' with vol[,1] and add volinp[2]
with vol[1,1]. The new 'volmat' will look like:

[,1]
[1,]   15.13
[2,]   61.61
[3,]   25.25
[4,]    0.00
[5,]    0.00

Then multiply 'dcmat' with the new 'volmat', and the 2nd column of output
matrix 'vol' will look like:

[,2]
[1,]  1.9669
[2,] 41.2665
[3,] 41.2232
[4,] 13.1199
[5,]  2.7775

Then again, replace the 'volmat' with vol[,2], add volinp[3] with vol[1,2] and
multiply the new 'volmat' with 'dcmat'. This replacement, addition,
multiplication, and dumping will continue up to the length of 'volinp' and the
final output matrix 'vol' will be something like:

[,1]    [,2]      [,3]    ...length(volinp)
[1,] 13.13   1.9669   0.645697  ...
[2,] 61.61  41.2665  24.488389  ...
[3,] 25.25  41.2232  40.419786  ...
[4,]  0.00  13.1199  22.116099  ...
[5,]  0.00   2.7775   7.670905  ...

Within my limited capacity, I've tried to come up with a solution but failed.

I'll appreciate your/others' help with gratefulness.

Regards,

Halim

---------------
Md. Abdul Halim
Assistant Professor
Department of Forestry and Environmental Science
Shahjalal University of Science and Technology,Sylhet-3114,
Cell: +8801714078386.
alt. e-mail: xou03 at yahoo.com

On Sat, 23 Nov 2013 14:10:12 -0800 (PST), arun wrote
> Hi,
> Could you show your expected output?  It is a bit unclear from the
description.
>
> On Saturday, November 23, 2013 2:00 PM, halim10-fes <halim10-
> fes at sust.edu> wrote: Dear R-friends,
>
> Hope you doing well. I've been trying to deal with the following
> problem for the couple of days but couldn't come up with a solution.
> It would be great if any of you could give some insight into it.
>
> I have three matrices like:
>
> dcvol<-matrix(c(0.13,0.61,0.25,0.00,0.00,0.00,0.52,0.37,0.09,0.00,
> 0.00,0.00,                 0.58,0.30,0.11,0.00,0.00,0.00,0.46,0.22,
> 0.00,0.00,0.00,0.00,                 0.09),nrow=5,ncol=5)
volinp<-
> matrix(c(100,0,0,0,0),nrow=5,ncol=1)
>
> scvol<-matrix(c(1:40),nrow=5,ncol=8)
>
> What I essentially want to do is to add each value in scvol[1,] with
> the volinp[1,1] and then multiply each new volinp with dcvol and
> finally put the outputs in a new matrix.
>
> Thanks in advance.
>
> Halim
> ---------------
> Md. Abdul Halim
> Assistant Professor
> Department of Forestry and Environmental Science
> Shahjalal University of Science and Technology,Sylhet-3114,
> Cell: +8801714078386.
> alt. e-mail: xou03 at yahoo.com
>
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