This topic answers some common questions about floating-point processing.
The topics describing floating-point precision make frequent reference to the compiler options that are grouped together in Floating-point and integer control in the XL Fortran Compiler Reference, 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.