# search for: dvec

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2003 Jun 02
1
Help with factorized argument in solve.QP
...an itself. That is, when factorized=TRUE, the Dmat argument should be a matrix R^(-1), such that the Hessian of the objective function is t(R) %*% R. I modified the example in the helpfile slightly to test this out: R = matrix(rnorm(9),3,3) R.inv = solve(R) Dmat = t(R) %*% R dvec = c(0,5,0) Amat = matrix(c(-4,-3,0,2,1,0,0,-2,1),3,3) bvec = c(-8,2,0) x1 = solve.QP(Dmat=Dmat, dvec=dvec, Amat=Amat, bvec=bvec, factorized=FALSE) x2 = solve.QP(Dmat=R.inv, dvec=dvec, Amat=Amat, bvec=bvec, factorized=TRUE) print(x1\$solution) print(x2\$solution) I wou...
2009 Feb 16
2
solve.QP with box and equality constraints
...general principle of creating box constraints by creating pairs of positive and negative values within the constraint matrix ( http://tolstoy.newcastle.edu.au/R/help/05/10/14251.html), but when I pass this expanded constraint matrix to solve.QP it complains that Amat and dvec are incompatible. How should I expand dvec (and consequently Dmat) to accomodate the larger Amat? Moreover, I am unclear how to apply the meq equality constraint across more than one cell (i.e. rows summing to one) although I have attempted a guess below. Any help warmly received. Selwyn. #######...
2005 Jan 13
1
how to use solve.QP
...<= w #<=1=bUp] to Amat <- rbind(-1, 1, -mu, mu) dim(bLo) <- c(n,1) dim(bUp) <- c(n,1) bvec <- rbind(-1, 1, mu.target, Inf, bLo, -bUp) zMat <- matrix(rep(0,2*n*n),ncol=n, nrow=n*2) zMat[,1] <- c(rep(1,n), rep(-1,n)) Amat <- t(rbind(Amat, zMat)) #So I set Dmat=Cov and set dvec=0 Dmat=Cov dvec=rep(0, nrow(Amat)) #The first two rows of Amat should be equality constraints (so weights sum to 1) meq <- 2 sol <- solve.QP(Dmat=Dmat, dvec=dvec, Amat=Amat, bvec=bvec, meq) sol
2013 Feb 21
0
About multivariate GARCH: DVEC and BEKK
Dear All, I attempted to fit a DVEC and a BEKK multivariate GARCH model, but am wondering which package to use. 1. I tried to use "rmgarch" package in R, but I couldn't find the subroutines for DVEC and BEKK. 2. I tried to find "rmgarch" package of R, which is not located on the official R site. This is...
2010 Dec 04
1
...matrix. Are there any (fast) packages that allows me to do QP with (large) semidefinite matrices? Example: t <- 100 y <- signalConvNoisy[1,] D <- crossprod(H,H) d <- crossprod(H,y) A <- cbind(rep(-1, nrow(H)), diag(ncol(H))) b0 <- c(t, rep(0, ncol(H))) sol <- solve.QP(Dmat=D, dvec = d, Amat = A, bvec = b0)\$solution Error in solve.QP(Dmat = D, dvec = d, Amat = A, bvec = b0) : matrix D in quadratic function is not positive definite! Thanks in advance, Andreas Jensen
2018 Mar 05
0
Interpret List Label as Date from Quantmod getOptionChain
...6" "2018-04-13" "2018-04-20" "2018-05-18" [8] "2018-06-15" "2018-08-17" "2018-09-21" "2018-10-19" "2018-11-16" "2019-01-18" "2019-06-21" [15] "2020-01-17" "2020-06-19" R> dvec <- anydate(names(aapl_total)) # helper variable R> ind <- dvec >= anydate("2018-04-01") & dvec <= anydate("2018-04-30") # one example R> ind [1] FALSE FALSE FALSE TRUE TRUE TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE R...
2018 Mar 05
2
Interpret List Label as Date from Quantmod getOptionChain
Hi Dirk, Thanks for your note. I understand that expiry dates are the dates that the option expires, so I don't think that I am confused about that (although the upper limits of one's confusion is difficult to accurately estimate). My lack of clarity come from treating those "dates" as actual dates as opposed to strings, which one could reasonably interpret them to be from
2004 Sep 01
0
not positive definite D matrix in quadprog
...s) #now all eigenvalues are positive: D.values.new <- eigen(D.vectors%*%D.quad%*%ginv(D.vectors),only.values=F)\$values D.values.new [1] 4.609489e+04 2.458166e+03 8.232288e+01 1.961199e+00 5.976441e-01 [6] 2.810968e-01 1.253140e-09 1.428534e-12 Dmat <- D.vectors%*%D.quad%*%ginv(D.vectors) dvec <- -c(-2910.533769,-2905.609008,-3012.223863,-16274.97455,-17222.46423,-18380.6 391,-357.8878464,-379.6371849) #this ensures that coefficients are positive: Amat <- matrix(0,8,8) diag(Amat) <- 1 bvec <- rep(0,8) #it says D is not positive definite ... solve.QP(Dmat,dvec,Amat,bvec=...
2005 Nov 29
1
I'm having difficulty figuring out how to implement the following set of constraints in Quadprog: 1). x1+x2+x3+x4=a1 2). x1+x2+x5+x6=a2 3). x1+x3+x5+x7=a3 4). x1+x2=b1 5). x1+x3=b2 6). x1+x5=b3 for the problem: MIN (x1-c1)2+(x2-c2)2+...+(x8-c8)2. As far a I understand, "solve.QP(Dmat, dvec, Amat, bvec, meq=0, factorized=FALSE)" reads contraints using an element-by-element multiplication, i.e. Amat'*x, not using the matrix-product, i.e. Amat'%*%x, required for the sums on the left-hand-side of 1-6). I would very much appreciate a suggestion on this problem. Thank you,...
2006 Nov 08
0
Solving a maximization problem using QUADPROD
...0) %*% b - 1/2 b^T b? # Assume we want to minimize: -(0 5 0) %*% b + 1/2 b^T b # under the constraints: A^T b >= b0 # with b0 = (-8,2,0)^T # and (-4 2 0) # A = (-3 1 -2) # ( 0 0 1) # we can use solve.QP.compact as follows: # library(quadprog) Dmat <- matrix(0,3,3) diag(Dmat) <- 1 dvec <- c(0,5,0) Aind <- rbind(c(2,2,2),c(1,1,2),c(2,2,3)) Amat <- rbind(c(-4,2,-2),c(-3,1,1)) bvec <- c(-8,2,0) solve.QP.compact(Dmat,dvec,Amat,Aind,bvec=bvec) Thanks, Serguei
2012 Mar 16
1