3.4.35 –fround={nearest|tozero|negative|positive}

Set the IEEE rounding mode in effect at startup.

The default is -fround=nearest.

To be effective, compile the main program with this option.

This option sets the IEEE 754 rounding mode that:

• Can be used by the compiler in evaluating constant expressions.

• Is established at runtime during the program initialization.

When the value is tozero, negative, or positive, the option sets the rounding direction to round-to-zero, round-to-negative-infinity, or round-to-positive-infinity, respectively, when the program begins execution. When -fround is not specified, -fround=nearest is used as the default and the rounding direction is round-to-nearest. The meanings are the same as those for the ieee_flags function. (See the “Floating–Point Arithmetic” chapter of the Fortran Programming Guide.)