The IFIP Working Group 2.5 on Numerical Software (IFIPWG2.5) wrote on 5th Septem-

ber 2007 to the IEEE Standards Committee concerned with revising the IEEE Floating-

Point Arithmetic Standards 754 and 854 (IEEE754R), expressing the unanimous

request of IFIPWG2.5 that the following requirement be included in the future computer

arithmetic standard:

For the data format double precision, interval arithmetic should be made

available at the speed of simple floating-point arithmetic.

IEEE754R (we believe) welcomed this development. They had before them a document

defining interval arithmetic operations but, to be the basis of a standards document, it

needed more detail. Members of the Interval Subroutine Library (ISL) team were asked

to comment, in an email from Ulrich Kulisch that enclosed one from Jim Demmel to Van

Snyder raising the issue. This paper provides ISL's comments.