I missed a couple line of codes in the previous e-mail. Here is whole code
again:

load <- matrix(c(3,0,1,4,1,3),nrow=3,ncol=2,byrow=TRUE)

l <- matrix(nrow=nrow(load),ncol=ncol(load))
for(i in 1:nrow(load)) {
for(j in 1:ncol(load)) { l[i,j]=paste("l",i,j,sep="")}}

for(i in 1:nrow(load)){
for(j in 1:ncol(load)){ assign(paste("l",i,j,sep=""),load[i,j]) }}

numericDeriv(quote(l11*l21+l12*l22), c(t(l),recursive=TRUE))

a <- paste(
paste(l[1,1],l[2,1],sep="*"),
paste(l[1,2],l[1,2],sep="*"),
sep="+"
)

numericDeriv(???a???, c(t(l),recursive=TRUE))

Thanks

On Fri, May 18, 2012 at 1:25 PM, Cengiz Zopluoğlu <cen.zop@gmail.com> wrote:

> Hi,
>
> I am stuck on something for a couple days, I am almost about to give up.
> This looks simple, but I can't figure out. I hope I can get some help here.
>
> I am trying to do some symbolic and numerical derivations. Let me explain
> the problem. Let's say, I have a matrix as follows:
>
> > load <- matrix(c(3,0,1,4,1,3),nrow=3,ncol=2,byrow=TRUE)
> >
> > load
>       [,1] [,2]
> [1,]    3    0
> [2,]    1    4
> [3,]    1    3
>
> I will create objects for each element of the matrix, and assign the
> matrix elements to these objects. These objects will be also an element of
> another matrix.
>
> l <- matrix(nrow=nrow(load),ncol=ncol(load))
> for(i in 1:nrow(load)) {
> for(j in 1:ncol(load)) { l[i,j]=paste("l",i,j,sep="")}}
>
> > l
>      [,1]  [,2]
> [1,] "l11" "l12"
> [2,] "l21" "l22"
> [3,] "l31" "l32"
>
> > l11
> [1] 3
> > l12
> [1] 0
> > l21
> [1] 1
> > l22
> [1] 4
> > l31
> [1] 1
> > l32
> [1] 3
>
> Let's say, I need to take the derivative of  (l11*l21+l12*l22) with
> respect to l11,l12,l21,l22,l31,l32.
>
> > numericDeriv(quote(l11*l21+l12*l22), c(t(l),recursive=TRUE))
> [1] 3
> attr(,"gradient")
>      [,1] [,2] [,3] [,4] [,5] [,6]
> [1,]    1    4    3    0    0    0
>
> Everything is fine up to this point. I need what I have. But, I don't want
> to manipulate the elements in "quote()" manually within the numericDeriv
> function. For instance, I want to call these elements from the matrix "l"
> as below:
>
> > a <- paste(
> + paste(l[1,1],l[2,1],sep="*"),
> + paste(l[1,2],l[1,2],sep="*"),
> + sep="+"
> + )
> > a
> [1] "l11*l21+l12*l12"
>
> Now, "a" is a character. Do you have any idea about how to use the
> character value "l11*l21+l12*l12" assigned to object "a" within the
> numericDeriv function. So, I can get the same result as above without
> manipulating the expression in quote() manually.
>
> Thanks
>
>
>
>
> --
>
> Cengiz Zopluoglu
>
>
>
>
>


-- 

Cengiz Zopluoglu

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