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Christian, I agree. This was also my point in my reply to Van. Best regards, Baker Christian Keil wrote:
If converting to a wider type, no rounding occurs.This depends upon whether one adopts the Kuki or Cody view of FP numbers: Are the unwritten bits random, or all zero? If one adopts the view that unwritten bits are all zero, then no rounding is needed. If one adopts the view that unwritten bits are random then downward "rounding" of negative lower bounds and upward "rounding" of positive upper bounds are needed. By "rounding" in this context I mean filling the new bits of the fraction with ones instead of zeroes. For positive lower bounds or negative upper bounds, the correct thing to do is fill the new bits of the fraction with zeroes.I don't think this is appropriate for bounds in intervals. We want these to be rigorous so for example a two bit upper bound of 1.0 is mandated to mean that every number contained in the interval is less than 1.0. 1.0001 cannot be inside the interval, therefore a widening should always return an upper bound like 1.0000 instead of 1.0111.
-- --------------------------------------------------------------- R. Baker Kearfott, rbk@xxxxxxxxxxxxx (337) 482-5346 (fax) (337) 482-5270 (work) (337) 993-1827 (home) URL: http://interval.louisiana.edu/kearfott.html Department of Mathematics, University of Louisiana at Lafayette (Room 217 Maxim D. Doucet Hall, 1403 Johnston Street) Box 4-1010, Lafayette, LA 70504-1010, USA ---------------------------------------------------------------