On Thu, 2005-04-14 at 18:35, Richard Henderson wrote: > On Thu, Apr 14, 2005 at 05:27:16PM +0200, François-Xavier Coudert wrote: > > No, since reading GFORTRAN_FPU_* variables changes the FPU mode when the > > library is loaded, while TR 15580 commands will be ran afterwards (during > > execution). > > You'll find that globally changing the rounding mode will screw up > libm functions. Which is pretty much going to make this useless. > > Further, when folks need rounding modes other than round-to-nearest, > they tend to need to switch rounding modes during the program too. > For instance, to perform the same calculation with both round-up and > round-down to get error bounds on the calculation. > > Thus I think an environment variable to do this is doubly useless.
Not all environments can change the rounding mode dynamically. For example, on the FPA co-processor for ARM, rounding is set by the instruction selected -- so the concept of having an environment variable to control this is meaningless. R.
