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problem.chgmqobj

Purpose
Change multiple quadratic coefficients in the objective function. If any of the coefficients does not exist already, new coefficients will be added to the objective function.
Synopsis
problem.chgmqobj(objqcol1, objqcol2, objqcoef)
Arguments
objqcol1 
Array containing the column index of the first variable in each quadratic term.
objqcol2 
Array containing the column index of the second variable in each quadratic term.
objqcoef 
New values for the coefficients. If an entry in objqcoef is 0, the corresponding entry will be deleted. These are the coefficients of the lower triangular part of the Hessian of the objective function.
Example
The following code results in an objective function with terms: [15x12 + 7x1x2]/2 
p.chgmqobj([x1,x1], [x1,x2], [15,3.5])
Further information
1. If objqcol1[t] is not equal to objqcol2[t], then both the matrix elements (objqcol1[t], objqcol2[t]) and (objqcol2[t], objqcol1[t]) are changed to leave the Hessian symmetric.
2. The quadratic matrix coefficients are implicitly divided by two. But since the coefficients for xixj ( i not equal to j) appear twice, only the coefficients for xi2 should be multiplied by two in the objqcoef array to account for the implicit division. See the example above.
3. chgmqobj is more efficient than repeated calls to problem.chgqobj and should be used in its place when several coefficients are to be changed.
Related topics
problem.chgcoef, problem.chgmcoef, problem.chgobj, problem.chgqobj, problem.getqobj.

Parent Topic Xpress problem methods

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