XPRSchgqobj

Purpose

Used to change a single quadratic coefficient in the objective function corresponding to the variable pair (icol,jcol) of the Hessian matrix.

Synopsis

int XPRS_CC XPRSchgqobj(XPRSprob prob, int icol, int jcol, double dval);

Arguments

prob	The current problem.
icol	Column index for the first variable in the quadratic term.
jcol	Column index for the second variable in the quadratic term.
dval	New value for the coefficient in the quadratic Hessian matrix. If an entry in dval is 0, the corresponding entry will be deleted.

Example

The following code adds the terms [15x₁² + 7x₁x₂]/2 to the objective function:

XPRSchgqobj(prob, 0, 0, 15);
XPRSchgqobj(prob, 0, 1, 3.5);

Further information

1. The columns icol and jcol must already exist in the matrix. If the columns do not exist, they must be added with the routine XPRSaddcols.

2. If icol is not equal to jcol, then both the matrix elements (icol, jcol) and (jcol, icol) are changed to leave the Hessian symmetric.