NAG FL Interface
e04vjf (nlp2_​sparse_​jacobian)

1 Purpose

2 Specification

3 Description

Call e04vgf (cw, lencw, ... )
Call e04vjf (nf, n, ... )
Call e04vlf ('Derivative Option = 0', cw, ... )
Call e04vhf (start, nf, ... )

4 References

5 Arguments

1: $\mathbf{nf}$ – Integer Input

On entry: $\mathit{nf}$, the number of problem functions in $F\left(x\right)$, including the objective function (if any) and the linear and nonlinear constraints. Simple upper and lower bounds on $x$ can be defined using the arguments xlow and xupp and should not be included in $F$.

Constraint: $\mathbf{nf}>0$.

2: $\mathbf{n}$ – Integer Input

On entry: $n$, the number of variables.

Constraint: $\mathbf{n}>0$.

3: $\mathbf{usrfun}$ – Subroutine, supplied by the user. External Procedure

usrfun must define the problem functions $F\left(x\right)$. This subroutine is passed to e04vjf as the external argument usrfun.

The specification of usrfun is:

Fortran Interface

Subroutine usrfun ( status, n, x, needf, nf, f, needg, leng, g, cuser, iuser, ruser) Integer, Intent (In) :: n, needf, nf, needg, leng Integer, Intent (Inout) :: status, iuser(*) Real (Kind=nag_wp), Intent (In) :: x(n) Real (Kind=nag_wp), Intent (Inout) :: f(nf), g(leng), ruser(*) Character (8), Intent (InOut) :: cuser(*)

C Header Interface

void  usrfun_ (Integer *status, const Integer *n, const double x[], const Integer *needf, const Integer *nf, double f[], const Integer *needg, const Integer *leng, double g[], char cuser[], Integer iuser[], double ruser[], const Charlen length_cuser)

C++ Header Interface

#include <nag.h> extern "C" { void  usrfun_ (Integer &status, const Integer &n, const double x[], const Integer &needf, const Integer &nf, double f[], const Integer &needg, const Integer &leng, double g[], char cuser[], Integer iuser[], double ruser[], const Charlen length_cuser) }

1: $\mathbf{status}$ – Integer Input/Output

On entry: indicates the first call to usrfun.

$\mathbf{status}=0$

There is nothing special about the current call to usrfun.

$\mathbf{status}=1$

e04vjf is calling your subroutine for the first time. Some data may need to be input or computed and saved.

On exit: may be used to indicate that you are unable to evaluate $F$ at the current $x$. (For example, the problem functions may not be defined there).

e04vjf evaluates $F\left(x\right)$ at random perturbation of the initial point $x$, say $x_p$. If the functions cannot be evaluated at $x_p$, you can set $\mathbf{status}=-1$, e04vjf will use another random perturbation.

If for some reason you wish to terminate the current problem, set $\mathbf{status}\le -2$.

2: $\mathbf{n}$ – Integer Input

On entry: $n$, the number of variables, as defined in the call to e04vjf.

3: $\mathbf{x}\left(\mathbf{n}\right)$ – Real (Kind=nag_wp) array Input

On entry: the variables $x$ at which the problem functions are to be calculated. The array $x$ must not be altered.

4: $\mathbf{needf}$ – Integer Input

On entry: indicates if f must be assigned during the call to usrfun (see f).

5: $\mathbf{nf}$ – Integer Input

On entry: $\mathit{nf}$, the number of problem functions.

6: $\mathbf{f}\left(\mathbf{nf}\right)$ – Real (Kind=nag_wp) array Input/Output

On entry: this will be set by e04vjf.

On exit: the computed $F\left(x\right)$ according to the setting of needf.

If $\mathbf{needf}=0$, f is not required and is ignored.

If $\mathbf{needf}>0$, the components of $F\left(x\right)$ must be calculated and assigned to f. e04vjf will always call usrfun with $\mathbf{needf}>0$.

To simplify the code, you may ignore the value of needf and compute $F\left(x\right)$ on every entry to usrfun.

7: $\mathbf{needg}$ – Integer Input

On entry: e04vjf will call usrfun with $\mathbf{needg}=0$ to indicate that g is not required.

8: $\mathbf{leng}$ – Integer Input

On entry: the dimension of the array g as declared in the (sub)program from which e04vjf is called.

9: $\mathbf{g}\left(\mathbf{leng}\right)$ – Real (Kind=nag_wp) array Input/Output

On entry: concerns the calculations of the derivatives of the function $f\left(x\right)$.

On exit: e04vjf will always call usrfun with $\mathbf{needg}=0$: g is not required to be set on exit but must be declared correctly.

10: $\mathbf{cuser}\left(*\right)$ – Character(8) array User Workspace

11: $\mathbf{iuser}\left(*\right)$ – Integer array User Workspace

12: $\mathbf{ruser}\left(*\right)$ – Real (Kind=nag_wp) array User Workspace

usrfun is called with the arguments cuser, iuser and ruser as supplied to e04vjf. You should use the arrays cuser, iuser and ruser to supply information to usrfun.

usrfun must either be a module subprogram USEd by, or declared as EXTERNAL in, the (sub)program from which e04vjf is called. Arguments denoted as Input must not be changed by this procedure.

Note: usrfun should not return floating-point NaN (Not a Number) or infinity values, since these are not handled by e04vjf. If your code inadvertently does return any NaNs or infinities, e04vjf is likely to produce unexpected results.

4: $\mathbf{iafun}\left(\mathbf{lena}\right)$ – Integer array Output

5: $\mathbf{javar}\left(\mathbf{lena}\right)$ – Integer array Output

6: $\mathbf{a}\left(\mathbf{lena}\right)$ – Real (Kind=nag_wp) array Output

On exit: define the coordinates $\left(i,j\right)$ and values $A_{ij}$ of the nonzero elements of the linear part $A$ of the function $F\left(x\right)=f\left(x\right)+Ax$.

In particular, nea triples $\left(\mathbf{iafun}\left(k\right),\mathbf{javar}\left(k\right),\mathbf{a}\left(k\right)\right)$ define the row and column indices $i=\mathbf{iafun}\left(k\right)$ and $j=\mathbf{javar}\left(k\right)$ of the element $A_{ij}=\mathbf{a}\left(k\right)$.

7: $\mathbf{lena}$ – Integer Input

On entry: the dimension of the arrays iafun, javar and a that hold $\left(i,j,A_{ij}\right)$ as declared in the (sub)program from which e04vjf is called. lena should be an overestimate of the number of elements in the linear part of the Jacobian.

Constraint: $\mathbf{lena}\ge 1$.

8: $\mathbf{nea}$ – Integer Output

On exit: is the number of nonzero entries in $A$ such that $F\left(x\right)=f\left(x\right)+Ax$.

9: $\mathbf{igfun}\left(\mathbf{leng}\right)$ – Integer array Output

10: $\mathbf{jgvar}\left(\mathbf{leng}\right)$ – Integer array Output

On exit: define the coordinates $\left(i,j\right)$ of the nonzero elements of $G$, the nonlinear part of the derivatives $J\left(x\right)=G\left(x\right)+A$ of the function $F\left(x\right)=f\left(x\right)+Ax$.

11: $\mathbf{leng}$ – Integer Input

On entry: the dimension of the arrays igfun and jgvar that define the varying Jacobian elements $\left(i,j,G_{ij}\right)$ as declared in the (sub)program from which e04vjf is called. leng should be an overestimate of the number of elements in the nonlinear part of the Jacobian.

Constraint: $\mathbf{leng}\ge 1$.

12: $\mathbf{neg}$ – Integer Output

On exit: the number of nonzero entries in $G$.

13: $\mathbf{x}\left(\mathbf{n}\right)$ – Real (Kind=nag_wp) array Input

On entry: an initial estimate of the variables $x$. The contents of $x$ will be used by e04vjf in the call of usrfun, and so each element of x should be within the bounds given by xlow and xupp.

14: $\mathbf{xlow}\left(\mathbf{n}\right)$ – Real (Kind=nag_wp) array Input

15: $\mathbf{xupp}\left(\mathbf{n}\right)$ – Real (Kind=nag_wp) array Input

On entry: contain the lower and upper bounds $l_x$ and $u_x$ on the variables $x$.

To specify a nonexistent lower bound ${\left[l_x\right]}_j=-\infty$, set $\mathbf{xlow}\left(j\right)\le -\mathit{bigbnd}$, where $\mathit{bigbnd}$ is the optional parameter Infinite Bound Size. To specify a nonexistent upper bound $\mathbf{xupp}\left(j\right)\ge \mathit{bigbnd}$.

To fix the $j$th variable (say, $x_j=\beta$, where $\left|\beta \right|<\mathit{bigbnd}$), set $\mathbf{xlow}\left(j\right)=\mathbf{xupp}\left(j\right)=\beta$.

16: $\mathbf{cw}\left(\mathbf{lencw}\right)$ – Character(8) array Communication Array

17: $\mathbf{lencw}$ – Integer Input

On entry: the dimension of the array cw as declared in the (sub)program from which e04vjf is called.

Constraint: $\mathbf{lencw}\ge 600$.

18: $\mathbf{iw}\left(\mathbf{leniw}\right)$ – Integer array Communication Array

19: $\mathbf{leniw}$ – Integer Input

On entry: the dimension of the array iw as declared in the (sub)program from which e04vjf is called.

Constraint: $\mathbf{leniw}\ge 600$.

20: $\mathbf{rw}\left(\mathbf{lenrw}\right)$ – Real (Kind=nag_wp) array Communication Array

21: $\mathbf{lenrw}$ – Integer Input

On entry: the dimension of the array rw as declared in the (sub)program from which e04vjf is called.

Constraint: $\mathbf{lenrw}\ge 600$.

22: $\mathbf{cuser}\left(*\right)$ – Character(8) array User Workspace

23: $\mathbf{iuser}\left(*\right)$ – Integer array User Workspace

24: $\mathbf{ruser}\left(*\right)$ – Real (Kind=nag_wp) array User Workspace

cuser, iuser and ruser are not used by e04vjf, but are passed directly to usrfun and may be used to pass information to this routine.

25: $\mathbf{ifail}$ – Integer Input/Output

On entry: ifail must be set to $0$, $-1\text{ or }1$. If you are unfamiliar with this argument you should refer to Section 4 in the Introduction to the NAG Library FL Interface for details.

For environments where it might be inappropriate to halt program execution when an error is detected, the value $-1\text{ or }1$ is recommended. If the output of error messages is undesirable, then the value $1$ is recommended. Otherwise, if you are not familiar with this argument, the recommended value is $0$. When the value $-\mathbf{1}\text{ or }\mathbf{1}$ is used it is essential to test the value of ifail on exit.

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

6 Error Indicators and Warnings

$\mathbf{ifail}=1$

On entry, $\mathbf{lencw}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{lencw}\ge 600$.

On entry, $\mathbf{leniw}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{leniw}\ge 600$.

On entry, $\mathbf{lenrw}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{lenrw}\ge 600$.

The initialization routine e04vgf has not been called.

$\mathbf{ifail}=2$

On entry, $\mathbf{lena}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{lena}\ge 1$.

On entry, $\mathbf{leng}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{leng}\ge 1$.

$\mathbf{ifail}=3$

User-supplied routine usrfun indicates that functions are undefined near given point x.

You have indicated that the problem functions are undefined by setting $\mathbf{status}=-1$ on exit from usrfun. This exit occurs if e04vjf is unable to find a point at which the functions are defined.

$\mathbf{ifail}=4$

User-supplied routine usrfun requested termination.

You have indicated the wish to terminate the call to e04vjf by setting status to a value $<-1$ on exit from usrfun.

$\mathbf{ifail}=5$

Either lena or leng is too small. Increase both of them and corresponding array sizes. $\mathbf{lena}=〈\mathit{\text{value}}〉$ and $\mathbf{leng}=〈\mathit{\text{value}}〉$.

$\mathbf{ifail}=6$

Cannot estimate Jacobian structure at given point x.

$\mathbf{ifail}=7$

Internal error: memory allocation failed when attempting to allocate workspace sizes $〈\mathit{\text{value}}〉$, $〈\mathit{\text{value}}〉$ and $〈\mathit{\text{value}}〉$. Please contact NAG.

$\mathbf{ifail}=8$

Internal memory allocation was insufficient. Please contact NAG.

$\mathbf{ifail}=-99$

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.

$\mathbf{ifail}=-399$

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.

$\mathbf{ifail}=-999$

Dynamic memory allocation failed.

See Section 9 in the Introduction to the NAG Library FL Interface for further information.

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example

10.1 Program Text

10.2 Program Data

10.3 Program Results