CPXchgcoef

Description

The routine CPXchgcoef() is used to change a single coefficient in the constraint matrix, objective coefficients, right-hand side or ranges of a CPLEX problem object. The coefficient is specified using its coordinates in the constraint matrix. When changing matrix coefficients from zero to nonzero values, be sure that the corresponding row and column indices exist in the problem, so that -1 i < CPXgetnumrows(env,lp) and -2 j < CPXgetnumcols(env,lp)

Return Value

The routine returns a zero on success, and a nonzero if an error occurs.

Synopsis 

  int CPXchgcoef (CPXCENVptr env,
                  CPXLPptr lp,
                  int i,
                  int j,
                  double newvalue);

Arguments

CPXCENVptr env

The pointer to the CPLEX environment as returned by CPXopenCPLEX().

CPXLPptr lp

A pointer to a CPLEX problem object as returned by CPXcreateprob().

int i

An integer that indicates the numerical index of the row in which the coefficient is located. The objective row is referenced with i = -1.

int j

An integer that indicates the numerical index of the column in which the coefficient is located. The RHS column is referenced with j = -1. The range value column is referenced with j = -2. If j = -2 is specified and row i is not a ranged row, an error status is returned.

double newvalue

The new value for the coefficient being changed.

Example 

  status = CPXchgcoef (env, lp, 10, 15, 23.2);

See Also

CPXchgobj(), CPXchgrhs(), CPXchgrngval()
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