Specifications

Using Callable System Routines
10.1 Deciding Which Routines to Use
• Algebraic function evaluation
• Complex function evaluation
• Complex exponentiation
• Miscellaneous function evaluation
If you want to maintain compatibility with future libraries and create portable
mathematical applications, Digital recommends that you use the DPML routines
available through the high-level language of your choice (for example, FORTRAN
or C) rather than using the call interface. This will guarantee the functioning
of the routines across platforms. Because of the complex relationship between
high-level languages and DPML routines, the behavior of direct calls to DPML
routines may change in future releases. DPML routines also provide significantly
higher performance and accuracy.
For more information about using DPML routines, refer to Digital Portable
Mathematics Library.♦
10.1.8 Event Synchronization
For event synchronization, use RTL routines or system services. Use RTL
routines to synchronize events with event flags. Use system services to
synchronize events with event flags, with a resource lock, and with an
asynchronous system trap (AST).
10.2 RTL Routines
The OpenVMS Common Run-Time Procedure Library (or the Run-Time Library)
is a set of language-independent procedures that perform a wide variety of
operations. These RTL routines follow the OpenVMS Calling Standard; they
are part of the Common Run-Time environment. The Common Run-Time
environment lets a program contain routines written in different languages,
so that you can call RTL routines from any language, thus increasing program
flexibility.
10.2.1 Organization of the Run-Time Library
The routines of the OpenVMS RTL are grouped according to the types of tasks
they perform; these groups are referred to as facilities. Each group or facility has
an associated prefix that is used in the routine name to identify that routine as a
member of a particular facility. Table 10–1 lists all the RTL facility prefixes and
the types of tasks each facility performs.
Table 10–1 Run-Time Library Facilities
Facility Prefix Types of Tasks Performed
DTK$ DECtalk routines that are used to control Digital’s DECtalk device
LIB$ Library routines that obtain records from devices, manipulate
strings, convert data types for I/O, allocate resources, obtain system
information, signal exceptions, establish condition handlers, enable
detection of hardware exceptions, and process cross-reference data
MTH$ Mathematics routines that perform arithmetic, algebraic, and
trigonometric calculations
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