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 [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.