Apple 1.1.2 DVD VCR Combo User Manual


 
Exception Handling
The IEEE standard defines five exceptions that indicate when an
exceptional event has occurred. They are
invalid operation
underflow
overflow
division by zero
inexact result
There are three ways an application can deal with exceptions:
Continue operation.
Stop on exceptions if the programmer thinks they will
invalidate results.
Include code to do something special when exceptions happen.
The IEEE standard lets programs deal with the exceptions in
reasonable ways. It defines the special values NaN (Not-a-
Number) and Infinity, which allow a program to continue
operation. The IEEE standard also defines exception flags, which
a program can test to detect exceptional events.
About the FPCE Technical Report
Even though many computers now conform to the IEEE standard,
the standard has suffered from a lack of high-level portability.
The reason is that the standard does not define bindings to high-
level languages; it only defines a programming environment.
For instance, the standard defines data formats that should be
supported but does not tell how these data formats should map
to variable types in high-level languages. It also specifies that
the user must be able to control rounding direction but falls short
of defining how the user is able to do so.
However, the definition of a binding is in progress for the C
programming language. The Floating-Point C Extensions (FPCE)
branch of the Numerical C Extensions Group (NCEG), or ANSI
X3J11.1, has proposed a general floating-point specification for
the C programming language, called the FPCE technical report,
that contains additional specifications for implementations that
comply with IEEE floating-point standards 754 and 854.
The FPCE technical report not only specifies how to implement
the requirements of the IEEE standards, but also requires some
additional functions, called transcendental functions
(sometimes called elementary functions). These functions are
consistent with the IEEE standard and can be used as building
iMalc Manual
Technical Considerations
Technical Considerations
34