🚀 go-pugleaf

> If you don't have such a feature then the cost of interval addition
> is dominated by the cost of emptying the pipe and the cost of the two
> additions is minor.  

It sounds to me as though there is some scope for compiler research
here:  if I have something like
	X = X - Y
	Z = Z + W
then you can halve the number of mode switches in a fairly obvious
way.  This should pay off spectacularly for vector operations:
	X(1:N) = X(1:N) - Y(1:N)
only needs one mode switch (provided the compiler keeps track of the
mode setting at the beginning of each basic block).

I think it would be instructive to look at the level 1 BLAS and a few
subroutines from LINPACK to see whether a plausible optimisation level
applied to Fortran-90 versions could reduce the cost of mode switching.
What exactly do the interval arithmetic operations look like when built
on top of IEEE 754 primitives?


-- 
Q:  What should I know about quicksort?   A:  That it is *slow*.
Q:  When should I use it?  A:  When you have only 256 words of main storage.