[R] portfolio optimization in R

[Boris Steipe]

Indeed.
Start here: 
http://www.r-bloggers.com/three-tips-for-posting-good-questions-to-r-help-and-stack-overflow/

and then read this: 
http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example

Then put some comments into your code about what you think it should do. Oh, and clean up the formatting.
Hope this helps.
B.



On Nov 19, 2014, at 11:29 PM, Esra Ulasan <esra_ulasan at icloud.com> wrote:

> Dear Sir/Madam,
> 
> I am a PhD candidate and writing my dissertation about portfolio optimization in R. However, I have some problems with the codes. It always give the dimension error. Could you help me to fix it?
> 
> Yours sincerely,
> 
> Here are the codes:
> 
> optimization <- function(x) {
>  mean <- colMeans(x)
>  names(mean) <-assets.names
>  p <- ncol(x)
>  n <- nrow(x)
>  M <- as.integer(p)
>  S <- cov(x)
>  invS<- solve(S)
>  u <- rep(1,p)
> 
> #w <- matrix(rep(0,p), nrow=p)
> #r <- seq(0,length=p); w <- cbind (diag(450));    #sum of 1 
> #constraint <- cbind(diag(450), rep(0, 450));  #non-negativity constraint
>  a <- matrix(rep(0,4), nrow=2)
>  a[1,1] <- u%*%invS%*%u; 
>  a[1,2] <- a[2,1] <- u%*%invS%*%mean
>  a[2,2] <-mean%*%invS%*%mean 
>  d <- a[1,1]*a[2,2]-a[1,2]*a[1,2] 
>  f <- (invS%*%(a[2,2]*u-a[1,2]*mean))/d 
>  g <- (invS%*%(-a[1,2]*u+a[1,1]*mean))/d
>  rho <- 0.5
>  r <- seq(0, rho,length= M)
>  w <- matrix(rep(0, p*M), nrow=p)
>  for(m in 1:M) w[,m] <- f+r[,m]*g
>  #w <- f+(rho*g)
>  w[,m] >=0
>  sum([,m])==1
>  s <- sqrt(a[1,1]*((r-a[1,2]/a[1,1])^2)/d+ 1/a[1,1]) 
>  ss <- sqrt(diag(S))
>  names(ss) <- assets.name
>  minp <- c(sqrt(1/a[1,1]), a[1,2]/a[1,1])
>  wmimp<- f+(a[1,2]/a[1,1])*g; 
>  tanp <- c(sqrt(a[2,2])/a[1,2], a[2,2]/a[1,2]) 
>  wtanp <- f+(a[2,2]/a[1,2])*g; 
>  return(solve(s, r, ss, p, minp, tanp, wminp, wtanp))
> }
> result=optimization(x)
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