[no subject]
When comparing MidRad methods with InfSup, Siegfried Rump wrote:
> The reason is first that matrix mid-rad IV-multiplication can use
> BLAS routines. Second it needs only 2 times to switch the rounding
> mode compared to (at best) nµ2 times for inf-sup multiplication.
A good InfSup implementation would avoid the cost of rounding mode
changes; the method used may be platform-specific. When directed
operations (or pipes) are available, there is no switching. Otherwise
one would most likely use sign reversal for one bound in the internal
representation. Efficient multiplication might still be a challenge
when intervals contain zero; I have not worked out the details...
Michel.
Sent: 2009-02-12 17:11:21 UTC