CPXXcopybase and CPXcopybase

The routine CPXXcopybase/CPXcopybase copies a basis into a CPLEX problem object.

int CPXXcopybase( CPXCENVptr env, CPXLPptr lp, int const * cstat, int const * rstat )

int CPXcopybase( CPXCENVptr env, CPXLPptr lp, int const * cstat, int const * rstat )

Description

The routine CPXXcopybase/CPXcopybase copies a basis into a CPLEX problem object. It is not necessary to copy a basis prior to optimizing an LP problem, but a good initial basis can increase the speed of optimization significantly. A basis does not need to be primal or dual feasible to be used by the optimizer.

Note: The basis is ignored by the optimizer if the parameter known as advanced start switch (CPXPARAM_Advance) is set to 0 (zero).

Table 1. Table 1: Values of basis status for columns in cstat[j]
`CPX_AT_LOWER`	`0`	variable at lower bound
`CPX_BASIC`	`1`	variable is basic
`CPX_AT_UPPER`	`2`	variable at upper bound
`CPX_FREE_SUPER`	`3`	variable free and nonbasic

Table 2. Table 2: Values of basis status for rows other than ranged rows in rstat[j]
`CPX_AT_LOWER`	`0`	associated slack, surplus, or artificial variable is nonbasic at value 0.0 (zero)
`CPX_BASIC`	`1`	associated slack, surplus, or artificial variable is basic

Table 3. Table 3: Values of basis status for ranged rows in rstat[j]
`CPX_AT_LOWER`	`0`	associated slack, surplus, or artificial variable is nonbasic at its lower bound
`CPX_BASIC`	`1`	associated slack, surplus, or artificial variable is basic
`CPX_AT_UPPER`	`2`	associated slack, surplus, or artificial variable is nonbasic at its upper bound

Arguments

env: A pointer to the CPLEX environment as returned by CPXXopenCPLEX/CPXopenCPLEX.
lp: A pointer to a CPLEX problem object as returned by CPXXcreateprob/CPXcreateprob.
cstat: An array containing the basis status of the columns in the constraint matrix. The length of the array is equal to the number of columns in the problem object. Possible values of the basis status of columns appear in Table 1.
rstat: An array containing the basis status of the slack, or surplus, or artificial variable associated with each row in the constraint matrix. The length of the array is equal to the number of rows in the CPLEX problem object. For rows other than ranged rows, the array element rstat[i] has the meaning in Table 2. For ranged rows, the array element rstat[i] has the meaning in Table 3.

Return

The routine returns 0 (zero) if successful and nonzero if an error occurs.

Example


status = CPXcopybase (env, lp, cstat, rstat);