# NAG CL Interfacee04tjc (handle_​set_​linconstr_​coeff)

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## 1Purpose

e04tjc is a part of the NAG optimization modelling suite and sets or modifies a single element in the linear constraint matrix of the problem.

## 2Specification

 #include
 void e04tjc (void *handle, Integer idlc, Integer icolbj, double bij, NagError *fail)
The function may be called by the names: e04tjc or nag_opt_handle_set_linconstr_coeff.

## 3Description

After the model has been fully or partially built by calling functions of the NAG optimization modelling suite, e04tjc may be used to set or modify a single element ${b}_{\mathrm{ij}}$ in the sparse linear constraint matrix $B$ previously defined by e04rjc. This might be particularly helpful when a linear constraint needs to be extended after new variables have been added to the model by e04tac.
See Section 4.1 in the E04 Chapter Introduction for more details about the NAG optimization modelling suite.

None.

## 5Arguments

1: $\mathbf{handle}$void * Input
On entry: the handle to the problem. It needs to be initialized (e.g., by e04rac) and must not be changed between calls to the NAG optimization modelling suite.
2: $\mathbf{idlc}$Integer Input
On entry: $i$, the number of the linear constraint, i.e., the row index of the element ${b}_{\mathrm{ij}}$ in the linear constraint matrix to be changed.
Constraint: $1\le {\mathbf{idlc}}\le {m}_{B}$, where ${m}_{B}$ is the total number of linear constraints in the problem.
3: $\mathbf{icolbj}$Integer Input
On entry: $j$, the column (variable) index of the element ${b}_{\mathrm{ij}}$.
Constraint: $1\le {\mathbf{icolbj}}\le n$, where $n$ is the total number of decision variables in the problem.
4: $\mathbf{bij}$double Input
On entry: ${b}_{\mathrm{ij}}$, the new value of the element in the linear constraint matrix $B$.
5: $\mathbf{fail}$NagError * Input/Output
The NAG error argument (see Section 7 in the Introduction to the NAG Library CL Interface).

## 6Error Indicators and Warnings

NE_ALLOC_FAIL
Dynamic memory allocation failed.
See Section 3.1.2 in the Introduction to the NAG Library CL Interface for further information.
NE_HANDLE
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.
NE_INDICES
On entry, ${\mathbf{icolbj}}=⟨\mathit{\text{value}}⟩$ and $n=⟨\mathit{\text{value}}⟩$.
Constraint: $1\le {\mathbf{icolbj}}\le n$.
On entry, ${\mathbf{idlc}}=⟨\mathit{\text{value}}⟩$ and ${m}_{B}=⟨\mathit{\text{value}}⟩$.
Constraint: $1\le {\mathbf{idlc}}\le {m}_{B}$.
NE_INTERNAL_ERROR
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact NAG for assistance.
See Section 7.5 in the Introduction to the NAG Library CL Interface for further information.
NE_NO_LICENCE
Your licence key may have expired or may not have been installed correctly.
See Section 8 in the Introduction to the NAG Library CL Interface for further information.
NE_PHASE
The problem cannot be modified right now, the solver is running.
NE_SETUP_ERROR
There are no linear constraints in the problem.

Not applicable.