Note: this routine is made available for users of the NAG AD Library who are not using dco/c++.

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2Specification

Fortran Interface
 Integer, Intent (Inout) :: ifail Type (c_ptr), Intent (Inout) :: cb_handle ADTYPE, Intent (Out) :: xa
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:
extern "C" {
}
The header declares five functions with names reflecting the type used for active real arguments. The actual function and type names are formed by replacing AD and ADTYPE in the above as follows:

3Description

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_AD_f. x10cj_AD_f can be used to extract an object of the type ADTYPE from the callback data object. In this way an object of the type ADTYPE 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.

None.

5Arguments

1: $\mathbf{cb_handle}$Pointer to AD Data 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: $\mathbf{xa}$ADTYPE Output
On exit: an object of the type ADTYPE, ${x}_{a}$, to be extracted from the callback data object.
3: $\mathbf{ifail}$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 $-\mathbf{1}$ 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).

6Error Indicators and Warnings

If on entry ${\mathbf{ifail}}=0$ or $-1$, explanatory error messages are output on the current error message unit (as defined by x04aaf).
Errors or warnings detected by the routine:
${\mathbf{ifail}}=1$
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.
${\mathbf{ifail}}=-99$
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.

Not applicable.