(!******************************************************
   Mosel Example Problems
   ======================

   file foliomiqc.mos
   ``````````````````
   Modeling a small MIQCQP problem 
   to perform portfolio optimization.
   -- Maximize return with limit on variance
      and limited number of assets ---
   
  (c) 2008 Fair Isaac Corporation
      author: S.Heipcke, July 2008, rev. Mar. 2013
*******************************************************!)

model "Portfolio optimization with MIQCQP"
 uses "mmxnlp"

 parameters
  MAXVAL = 0.3                      ! Max. investment per share
  MINAM = 0.5                       ! Min. investment into N.-American values
  MAXNUM = 4                        ! Max. number of different assets
  MAXVAR = 1.25                     ! Max. allowed variance
 end-parameters

 declarations
  SHARES = 1..10                    ! Set of shares
  NA: set of integer                ! Set of shares issued in N.-America
  RET: array(SHARES) of real        ! Estimated return in investment
  VAR: array(SHARES,SHARES) of real ! Variance/covariance matrix of
                                    ! estimated returns
 end-declarations

 initializations from "folioqp.dat"
  RET NA VAR
 end-initializations

 declarations
  frac: array(SHARES) of mpvar      ! Fraction of capital used per share
  buy: array(SHARES) of mpvar       ! 1 if asset is in portfolio, 0 otherwise
 end-declarations

! Objective: total return
 Return:= sum(s in SHARES) RET(s)*frac(s) 

! Minimum amount of North-American values
 sum(s in NA) frac(s) >= MINAM

! Spend all the capital
 sum(s in SHARES) frac(s) = 1
 
! Limit variance
 sum(s,t in SHARES) VAR(s,t)*frac(s)*frac(t) <= MAXVAR

! Upper bounds on the investment per share
 forall(s in SHARES) frac(s) <= MAXVAL

! Limit the total number of assets
 sum(s in SHARES) buy(s) <= MAXNUM

 forall(s in SHARES) do
  buy(s) is_binary
  frac(s) <= buy(s)
 end-do

 setparam("XPRS_verbose", true)
! Solve the problem
 maximize(Return)

! Solution printing
 writeln("With a max. variance of ", MAXVAR, " and at most ", MAXNUM,
          " assets,\n total return is ", getsol(Return))
 forall(s in SHARES) writeln(s, ": ", getsol(frac(s))*100, "%")  

end-model