Partial Table-of-Contents
This section answers some common questions about floating-point processing,
such as:
- How can I get predictable, consistent results?
- How can I get the fastest or the most accurate results?
- How can I detect, and possibly recover from, exception conditions?
- Which compiler options can I use for floating-point
calculations?
- Related Information:
-
This section makes frequent reference to the compiler options that are grouped
together in Options for Floating-Point Processing, especially the -qfloat Option. The XL Fortran compiler also provides
three intrinsic modules for exception handling and IEEE arithmetic support to
help you write IEEE module-compliant code that can be more portable.
See IEEE Modules and Support in the
XL Fortran Language Reference for details.
The use of the compiler options for floating-point calculations affects the
accuracy, performance, and possibly the correctness of floating-point
calculations. Although the default values for the options were chosen
to provide efficient and correct execution of most programs, you may need to
specify nondefault options for your applications to work the way you
want. We strongly advise you to read this section before using these
options.
- Note:
- The discussions of single-, double-, and extended-precision calculations in
this section all refer to the default situation, with -qrealsize=4
and no -qautodbl specified. If you change these settings, keep
in mind that the size of a Fortran REAL, DOUBLE PRECISION,
and so on may change, but single precision, double precision, and extended
precision (in lowercase) still refer to 4-, 8-, and 16-byte entities
respectively.
The information in this section relates to floating-point processing on the
PowerPC family of processors.
