# NAG CL Interfaced02npc (dae_​dassl_​linalg)

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## 1Purpose

d02npc is a setup function which you must call prior to d02nec and after a call to d02mwc, if the Jacobian is to be considered as having a banded structure.

## 2Specification

 #include
 void d02npc (Integer neq, Integer ml, Integer mu, Integer icom[], Integer licom, NagError *fail)
The function may be called by the names: d02npc, nag_ode_dae_dassl_linalg or nag_dae_ivp_dassl_linalg.

## 3Description

A call to d02npc specifies that the Jacobian to be used is banded in structure. If d02npc is not called before a call to d02nec then the Jacobian is assumed to be full.

None.

## 5Arguments

1: $\mathbf{neq}$Integer Input
On entry: the number of differential-algebraic equations to be solved.
Constraint: $1\le {\mathbf{neq}}$.
2: $\mathbf{ml}$Integer Input
On entry: $ml$, the number of subdiagonals in the band.
Constraint: $0\le {\mathbf{ml}}\le {\mathbf{neq}}-1$.
3: $\mathbf{mu}$Integer Input
On entry: $mu$, the number of superdiagonals in the band.
Constraint: $0\le {\mathbf{mu}}\le {\mathbf{neq}}-1$.
4: $\mathbf{icom}\left[{\mathbf{licom}}\right]$Integer Communication Array
icom is used to communicate details of the integration from d02mwc and details of the banded structure of the Jacobian to d02nec.
5: $\mathbf{licom}$Integer Input
On entry: the dimension of the array icom.
Constraint: ${\mathbf{licom}}\ge 50+{\mathbf{neq}}$.
6: $\mathbf{fail}$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.
On entry, argument $⟨\mathit{\text{value}}⟩$ had an illegal value.
NE_INITIALIZATION
Either the initialization function has not been called prior to the first call of this function or the communication array has become corrupted.
NE_INT
On entry, licom is too small: ${\mathbf{licom}}=⟨\mathit{\text{value}}⟩$.
On entry, ${\mathbf{ml}}=⟨\mathit{\text{value}}⟩$.
Constraint: ${\mathbf{ml}}\ge 0$.
On entry, ${\mathbf{mu}}=⟨\mathit{\text{value}}⟩$.
Constraint: ${\mathbf{mu}}\ge 0$.
On entry, ${\mathbf{neq}}=⟨\mathit{\text{value}}⟩$.
Constraint: ${\mathbf{neq}}\ge 1$.
NE_INT_2
On entry, ${\mathbf{ml}}=⟨\mathit{\text{value}}⟩$ and ${\mathbf{neq}}=⟨\mathit{\text{value}}⟩$.
Constraint: ${\mathbf{ml}}\le {\mathbf{neq}}-1$.
On entry, ${\mathbf{mu}}=⟨\mathit{\text{value}}⟩$ and ${\mathbf{neq}}=⟨\mathit{\text{value}}⟩$.
Constraint: ${\mathbf{mu}}\le {\mathbf{neq}}-1$.
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.

Not applicable.