Set the IEEE rounding mode in effect at startup.
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.)