[R] Optimizing variables represented in a matrix

[David Winsemius]

On May 31, 2012, at 7:37 AM, <nataraj at orchidpharma.com> <nataraj at orchidpharma.com 
 > wrote:

>
> Dear R-list members,
>
> I have a matrix with non-numeric variables in it and I have to  
> optimize the variables of the matrix in a formula using optim  
> routine of the stats4 package. I know the matrix can only take  
> numeric data

Some of the things you think you know,  are not so:

 > exvec <- c('0.05V1+V2', '0.31V1', '0.05V1', '0.31V1', '0.3V1+V2',  
'0.5V1', '0.05V1', '0.5V1', '0.1V1+V2')
 > matrix(exvec, 3,3)
      [,1]        [,2]       [,3]
[1,] "0.05V1+V2" "0.31V1"   "0.05V1"
[2,] "0.31V1"    "0.3V1+V2" "0.5V1"
[3,] "0.05V1"    "0.5V1"    "0.1V1+V2"

> and so I would like to  know how to store non-numeric variables  
> inside a matrix.
>
> Say for example: The 3X3 matrix is     0.05V1+V2    0.31V1         
> 0.05V1                                                    
> 0.31V1       0.3V1+V2       
> 0.5V1                                          0.05V1        
> 0.5V1         0.1V1+V2
>
> The matrix is only for an example and the real matrix that I want to  
> use is a 15X15 matrix ,here I would like to optimize the values of  
> V1 and V2 using a formula.

Whether that plan makes sense seems problematic, but that wasn't your  
question.

>
> Could you please help me how to go about to represent the matrix in R.

I'm guessing you have thoughts of evaluating these expressions. They  
are not valid R expressions, however. You have some further study to do.

-- 

David Winsemius, MD
West Hartford, CT