Settings help

## 2Specification

Fortran Interface
 Integer, Intent (In) :: m, n, lda Integer, Intent (Inout) :: ifail Integer, Intent (Out) :: ipiv(min(m,n)) ADTYPE, Intent (Inout) :: a(lda,*) Type (c_ptr), Intent (Inout) :: ad_handle
Corresponding to the overloaded C++ function, the Fortran interface provides five routines with names reflecting the type used for active real arguments. The actual subroutine and type names are formed by replacing AD and ADTYPE in the above as follows:
#include <dco.hpp>
namespace nag {
 void f07ad ( void *&ad_handle, const Integer &m, const Integer &n, ADTYPE a[], const Integer &lda, Integer ipiv[], Integer &ifail)
}
}
The function is overloaded on ADTYPE which represents the type of active arguments. ADTYPE may be any of the following types:
double,
dco::ga1s<double>::type,
dco::gt1s<double>::type

## 3Description

f07adf (dgetrf) computes the $LU$ factorization of a real $m×n$ matrix. For further information see Section 3 in the documentation for f07adf (dgetrf).

## 4References

Golub G H and Van Loan C F (1996) Matrix Computations (3rd Edition) Johns Hopkins University Press, Baltimore

## 5Arguments

In addition to the arguments present in the interface of the primal routine, f07ad includes some arguments specific to AD.
A brief summary of the AD specific arguments is given below. For the remainder, links are provided to the corresponding argument from the primal routine. A tooltip popup for all arguments can be found by hovering over the argument name in Section 2 and in this section.
On entry: a handle to the AD configuration data object, as created by x10aa.
2: m – Integer Input
3: n – Integer Input
4: a(lda, $*$) – ADTYPE array Input/Output
5: lda – Integer Input
6: ipiv($\mathrm{min}\phantom{\rule{0.125em}{0ex}}\left({\mathbf{m}},{\mathbf{n}}\right)$) – Integer array Output
7: ifail – Integer Input/Output
On entry: must be set to $0$, .
On exit: any errors are indicated as described in Section 6.

## 6Error Indicators and Warnings

f07ad uses the standard NAG ifail mechanism. Any errors indicated via info values returned by f07adf may be indicated with the same value returned by ifail. In addition, this routine may return:
${\mathbf{ifail}}=-89$
See Section 4.8.2 in the NAG AD Library Introduction for further information.
${\mathbf{ifail}}=-199$
The routine was called using a mode that has not yet been implemented.
${\mathbf{ifail}}=-443$
This check is only made if the overloaded C++ interface is used with arguments not of type double.
${\mathbf{ifail}}=-444$
A C++ exception was thrown.
The error message will show the details of the C++ exception text.
${\mathbf{ifail}}=-899$
Dynamic memory allocation failed for AD.
See Section 4.8.1 in the NAG AD Library Introduction for further information.

Not applicable.

None.

## 10Example

The following examples are variants of the example for f07adf (dgetrf), modified to demonstrate calling the NAG AD Library.
Description of the primal example.
This example computes the $LU$ factorization of the matrix $A$, where
 $A= ( 1.80 2.88 2.05 -0.89 5.25 -2.95 -0.95 -3.80 1.58 -2.69 -2.90 -1.04 -1.11 -0.66 -0.59 0.80 ) .$

Language Source File Data Results