Floating-point and integer control

Specifying the details of how your applications perform calculations can allow you to take better advantage of your system's floating-point performance and precision, including how to direct rounding. However, keep in mind that strictly adhering to IEEE floating-point specifications can impact the performance of your application. Using the options in the following table, you can control trade-offs between floating-point performance and adherence to IEEE standards. Some of these options also allow you to control certain aspects of integer calculations.

Table 1. Floating-point and integer control options
Option name	@PROCESS directive	Description
-qautodbl	AUTODBL	Provides an automatic means of converting single-precision floating-point calculations to double-precision and of converting double-precision calculations to extended-precision.
-qdpc	DPC	Increases the precision of real constants for maximum accuracy, when assigning real constants to DOUBLE PRECISION variables.
-qenum	None.	Specifies the range of the enumerator constant and enables storage size to be determined.
-qfloat	FLOAT	Selects different strategies for speeding up or improving the accuracy of floating-point calculations.
-qieee, -y	IEEE	Specifies the rounding mode that the compiler will use when it evaluates constant floating-point expressions at compile time.
-qintlog	INTLOG	Specifies that you can mix integer and logical data entities in expressions and statements.
-qintsize	INTSIZE	Sets the size of default INTEGER and LOGICAL data entities that have no length or kind specified.
-qrealsize	REALSIZE	Sets the default size of REAL, DOUBLE PRECISION, COMPLEX, and DOUBLE COMPLEX values.
-qstrictieeemod	STRICTIEEEMOD	Specifies whether the compiler will adhere to the Fortran 2003 IEEE arithmetic rules for the ieee_arithmetic and ieee_exceptions intrinsic modules.