After the model has been fully or partially built by calling routines of the NAG optimization modelling suite, e04tjf may be used to set or modify a single element

b_{ij}

in the sparse linear constraint matrix

B

previously defined by e04rjf. This might be particularly helpful when a linear constraint needs to be extended after new variables have been added to the model by e04taf.

See Section 3.1 in the E04 Chapter Introduction for more details about the NAG optimization modelling suite.

4 References

None.

5 Arguments

1: $handle$ – Type (c_ptr) Input: On entry: the handle to the problem. It needs to be initialized (e.g., by e04raf) and must not be changed between calls to the NAG optimization modelling suite.
2: $idlc$ – Integer Input: On entry: $i$ , the number of the linear constraint, i.e., the row index of the element $b_{ij}$ in the linear constraint matrix to be changed.

Constraint: $1 \leq idlc \leq m_{B}$ , where $m_{B}$ is the total number of linear constraints in the problem.
3: $icolbj$ – Integer Input: On entry: $j$ , the column (variable) index of the element $b_{ij}$ .

Constraint: $1 \leq icolbj \leq n$ , where $n$ is the total number of decision variables in the problem.
4: $bij$ – Real (Kind=nag_wp) Input: On entry: $b_{ij}$ , the new value of the element in the linear constraint matrix $B$ .
5: $ifail$ – Integer Input/Output: On entry: ifail must be set to $0$ , $−1$ or $1$ to set behaviour on detection of an error; these values have no effect when no error is detected.
A value of $0$ causes the printing of an error message and program execution will be halted; otherwise program execution continues. A value of $−1$ means that an error message is printed while a value of $1$ means that it is not.

If halting is not appropriate, the value $−1$ or $1$ is recommended. If message printing is undesirable, then the value $1$ is recommended. Otherwise, the value $−1$ is recommended. When the value $- 1$ or $1$ is used it is essential to test the value of ifail on exit.

On exit: $ifail = 0$ unless the routine detects an error or a warning has been flagged (see Section 6).

6 Error Indicators and Warnings

If on entry

ifail = 0

−1

, explanatory error messages are output on the current error message unit (as defined by x04aaf).

Errors or warnings detected by the routine:

$ifail = 1$: The supplied handle does not define a valid handle to the data structure for the NAG optimization modelling suite. It has not been properly initialized or it has been corrupted.

$ifail = 2$: The problem cannot be modified right now, the solver is running.

$ifail = 3$: There are no linear constraints in the problem.

$ifail = 8$: On entry, $icolbj = ⟨ value ⟩$ and $n = ⟨ value ⟩$ .
Constraint: $1 \leq icolbj \leq n$ .

On entry, $idlc = ⟨ value ⟩$ and $m_{B} = ⟨ value ⟩$ .
Constraint: $1 \leq idlc \leq m_{B}$ .

$ifail = - 99$: An unexpected error has been triggered by this routine. Please contact NAG.
See Section 7 in the Introduction to the NAG Library FL Interface for further information.

$ifail = - 399$: Your licence key may have expired or may not have been installed correctly.
See Section 8 in the Introduction to the NAG Library FL Interface for further information.