# NAG CL Interfacee04tec (handle_​set_​linobj_​coeff)

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## 1Purpose

e04tec is a part of the NAG optimization modelling suite and sets or modifies a single element in the linear objective function of the problem.

## 2Specification

 #include
 void e04tec (void *handle, Integer idxci, double ci, NagError *fail)
The function may be called by the names: e04tec or nag_opt_handle_set_linobj_coeff.

## 3Description

After the model has been fully or partially built by calling functions from the NAG optimization modelling suite, e04tec may be used to set or modify a single element ${c}_{i}$ in the (possibly sparse) linear objective function ${c}^{\mathrm{T}}x$. This might be particularly helpful when the objective function 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: $\mathbf{idxci}$Integer Input
On entry: $i$, the index of the element ${c}_{i}$ in the linear objective function.
Constraint: $1\le {\mathbf{idxci}}\le n$, where $n$ is the total number of decision variables in the problem.
3: $\mathbf{ci}$double Input
On entry: ${c}_{i}$, the new value of the element in the linear objective function.
4: $\mathbf{fail}$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, ${\mathbf{idxci}}=⟨\mathit{\text{value}}⟩$ and $n=⟨\mathit{\text{value}}⟩$.
Constraint: $1\le {\mathbf{idxci}}\le n$.
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
The objective function is not linear.

Not applicable.

## 8Parallelism and Performance

Background information to multithreading can be found in the Multithreading documentation.
e04tec is not threaded in any implementation.