This function is called by optimize.portfolio to solve minimum variance or maximum quadratic utility problems
gmv_opt(R, constraints, moments, lambda, target, lambda_hhi, conc_groups,
solver = "quadprog", control = NULL)
xts object of asset returns
object of constraints in the portfolio object extracted with get_constraints
object of moments computed based on objective functions
risk_aversion parameter
target return value
concentration aversion parameter
list of vectors specifying the groups of the assets.
solver to use
list of solver control parameters
Ross Bennett