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Nate, On 5/12/2010 8:07 AM, Nate Hayes wrote:
John Pryce wrote:
. . .
Nate, you point out mid-rad can save memory, hence bandwidth, on large interval calculations. But the saving is always less than 50%, ne c'est pas? because one has to store the "mid" value to full precision. If you had a method that saves an order or two of magnitude, it would be more convincing. But that usually comes from an improved algorithm.John, I think you don't know what you're talking about. Amdahl's Law is nonlinear. When you're already above 99% parallel, reducing the sequential portion of a program by a very tiny amount can mean the difference between 1,000X and 10,000X speedups.
Nate, I've very puzzled by this. John's point was that the "mid" in mid-rad usually needs to be stored in full precision, while only the "rad" part could be economized. What does that have to do with Amdahl's law? Please explain or give an example. Where was John incorrect? Baker -- --------------------------------------------------------------- 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 ---------------------------------------------------------------