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Working with Linear Equality Constraints Using PortfolioCVaR Object

Linear equality constraints are optional linear constraints that impose systems of equalities on portfolio weights (seeLinear Equality Constraints). Linear equality constraints have propertiesAEquality, for the equality constraint matrix, andbEquality, for the equality constraint vector.

Setting Linear Equality Constraints Using thePortfolioCVaRFunction

The properties for linear equality constraints are set using thePortfolioCVaRobject. Suppose that you have a portfolio of five assets and want to ensure that the first three assets are 50% of your portfolio. To set this constraint:

一个= (1 1 1 0 0);b = 0.5;p = PortfolioCVaR('AEquality', A,'bEquality', b); disp(p.NumAssets) disp(p.AEquality) disp(p.bEquality)
5 1 1 1 0 0 0.5000

Setting Linear Equality Constraints Using thesetEqualityandaddEqualityFunctions

You can also set the properties for linear equality constraints usingsetEquality. Suppose that you have a portfolio of five assets and want to ensure that the first three assets are 50% of your portfolio. Given aPortfolioCVaRobjectp, usesetEqualityto set the linear equality constraints:

一个= (1 1 1 0 0);b = 0.5;p = PortfolioCVaR; p = setEquality(p, A, b); disp(p.NumAssets) disp(p.AEquality) disp(p.bEquality)
5 1 1 1 0 0 0.5000

Suppose that you want to add another linear equality constraint to ensure that the last three assets also constitute 50% of your portfolio. You can set up an augmented system of linear equalities or useaddEqualityto build up linear equality constraints. For this example, create another system of equalities:

p = PortfolioCVaR; A = [ 1 1 1 0 0 ];% first equality constraintb = 0.5;p = setEquality(p, A, b); A = [ 0 0 1 1 1 ];% second equality constraintb = 0.5;p = addEquality(p, A, b); disp(p.NumAssets) disp(p.AEquality) disp(p.bEquality)
5 1 1 1 0 0 0 0 1 1 1 0.5000 0.5000

ThePortfolioCVaRobject,setEquality, andaddEqualityimplement scalar expansion on thebEqualityproperty based on the dimension of the matrix in theAEqualityproperty.

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