x10cj: FL CL CPP AD

NAG AD Library
x10cj_a1w_f (callback_read_type_a1w)

Note: a1w denotes that first order adjoints are computed in working precision; this has the corresponding argument type nagad_a1w_w_rtype. Further implementations, for example for higher order differentiation or using the tangent linear approach, may become available at later marks of the NAG AD Library. The method of codifying AD implementations in the routine name and corresponding argument types is described in the NAG AD Library Introduction.

Keyword Search:

NAG Library Manual, Mark 27.1

Interfaces: FL CL CPP AD

NAG AD Interface Introduction

X10 (Adutils) Chapter Contents

X10 (Adutils) Chapter Introduction

x10cj: FL CL CPP AD

▸▿ Contents

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

6 Error Indicators and Warnings

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example

1 Purpose

x10cj_a1w_f reads an object of the type nagad_a1w_w_rtype from a callback data object created by x10ba_a1w_f.

2 Specification

Fortran Interface

Subroutine x10cj_a1w_f (

cb_handle, xa, ifail)

Integer, Intent (Inout)	::	ifail
Type (c_ptr), Intent (Inout)	::	cb_handle
Type (nagad_a1w_w_rtype), Intent (Out)	::	xa

C++ Header Interface

#include <nagad.h>

extern "C" {

void	x10cj_a1w_f_ (void *&cb_handle, nagad_a1w_w_rtype &xa, Integer &ifail)

}

The routine may be called by the names x10cj_a1w_f or nagf_adutils_callback_read_type_a1w.

3 Description

For routines where it is necessary to perform callback operations via one or more companion callbacks, data must be passed between the procedure argument and any such companion callback via a callback data object as created by x10ba_a1w_f. x10cj_a1w_f can be used to extract an object of the type nagad_a1w_w_rtype from the callback data object. In this way an object of the type nagad_a1w_w_rtype can be communicated between a procedure argument and its companion callbacks.

Note that writing to and reading from a callback data object must be performed in strict order without omission. Reading a data item from the object is equivalent to removing that item from a data stack; reading is, therefore, not passive, but updates the callback data object.

4 References

None.

5 Arguments

1: $cb_handle$ – Type (c_ptr) Input/Output: On entry: will contain a handle to the callback data object.

On exit: will contain a handle to the updated callback data object, with data item removed from data stack.
2: $xa$ – Type (nagad_a1w_w_rtype) Output: On exit: an object of the type nagad_a1w_w_rtype, $x_{a}$ , to be extracted from the callback data object.
3: $ifail$ – Integer Input/Output: On entry: ifail must be set to $0$ , $- 1$ or $1$ to set behaviour on detection of an error; these values have no effect when no error is detected.
A value of $0$ causes the printing of an error message and program execution will be halted; otherwise program execution continues. A value of $- 1$ means that an error message is printed while a value of $1$ means that it is not.

If halting is not appropriate, the value $- 1$ or $1$ is recommended. If message printing is undesirable, then the value $1$ is recommended. Otherwise, the value $0$ is recommended. When the value $- 1$ or $1$ is used it is essential to test the value of ifail on exit.

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

6 Error Indicators and Warnings

If on entry

ifail = 0

- 1

, explanatory error messages are output on the current error message unit (as defined by x04aaf).

Errors or warnings detected by the routine:

$ifail = 1$: On entry, cb_handle does not define a valid handle to a NAG AD callback data object. It has not been initialized or has been corrupted.

$ifail = - 99$: 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.

$ifail = - 399$: 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.