# [R] Problems dealing with matrices

arun smartpink111 at yahoo.com
Sun Nov 24 16:45:24 CET 2013

```Hi Halim,
I guess this works for you.  Modifying Jeff's solution:

volinp<-c(0,0.000467,0.002762,0.008621,0.020014,0.038907,0.067094)
vol1 <- dcmat %*% (volmat +wt)
for(idx in seq_along(volinp)[-1]){
vol1 <- cbind(vol1,dcmat %*% (vol1[,idx-1] + volinp[idx] *wt))
}

#or

vol <- matrix( NA, nrow=5, ncol=length( volinp ) )
vol[ , 1 ] <- dcmat %*% ( volmat + wt )

for ( idx in seq_along(volinp)[ -1 ] ) {
vol[ , idx ] <- dcmat %*% ( vol[ , idx-1 ] + volinp[idx] * wt )
}
identical(vol,vol1)
#[1] TRUE

A.K.

On Sunday, November 24, 2013 7:16 AM, halim10-fes <halim10-fes at sust.edu> wrote:
Hi Arun,

OK, no problem. Thank you very much for your attention. I've posted an annex

Off-topic: You're a very helpful man. I like your attitude to helping others.

Take care.

Halim

On Sun, 24 Nov 2013 01:18:18 -0800 (PST), arun wrote
> Hi,
> Please disregard my earlier message. Looks like Jeff understand it
> better and answered it. Regards, Arun
>
> On Sunday, November 24, 2013 3:23 AM, arun <smartpink111 at yahoo.com> wrote:
> Hi,
> I am finding some inconsistency with your description.
> For example:
> volinp[1]+volmat[1,1]
> [1] 101
>
> On Sunday, November 24, 2013 1:52 AM, halim10-fes <halim10-
> fes at sust.edu> wrote:
>
> 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.
> >
> >
> > 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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> > ______________________________________________
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guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
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---------------
Md. Abdul Halim
Assistant Professor
Department of Forestry and Environmental Science
Shahjalal University of Science and Technology,Sylhet-3114,