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 Posted Wednesday, October 19, 2011 12:14 AM
 SSCrazy Group: General Forum Members Last Login: Yesterday @ 3:00 AM Points: 2,816, Visits: 1,593
 Comments posted to this topic are about the item Pascals Triangle, Home Work and Root Cause Analysis
Post #1192655
 Posted Wednesday, October 19, 2011 2:06 AM
 Ten Centuries Group: General Forum Members Last Login: 2 days ago @ 5:14 AM Points: 1,280, Visits: 713
 Excellent article.Even better, I see you used to work in Manchester!Paul.Manchester,UK.
Post #1192689
 Posted Wednesday, October 19, 2011 7:18 AM
 UDP Broadcaster Group: General Forum Members Last Login: Yesterday @ 6:51 AM Points: 1,461, Visits: 1,815
 I enjoyed your article because it was relevant on multiple levels. Thank you for a well-written article!
Post #1192835
 Posted Wednesday, October 19, 2011 7:50 AM
 Forum Newbie Group: General Forum Members Last Login: Thursday, December 05, 2013 11:20 AM Points: 6, Visits: 236
 Hi David, This is fantastic! I can find many uses for this..Thanks! John R
Post #1192853
 Posted Wednesday, October 19, 2011 8:10 AM
 Ten Centuries Group: General Forum Members Last Login: Yesterday @ 7:38 AM Points: 1,178, Visits: 1,533
 Good article.Of course, the point you omitted is how the actual probability of any given failure alters the calculations. With the lottery example, because each of the numbers is (supposedly) equally likely to be chosen, Pascal's triangle is a perfect model, and shows the true (im)probability of winning.With the car example, QA testing ensures that parts generally have a much higher probability of working than failing, thus although there's only one way for the whole system to work perfectly, it's more likely than the millions of ways it can fail.
Post #1192869
 Posted Wednesday, October 19, 2011 9:50 AM
 SSCrazy Group: General Forum Members Last Login: Yesterday @ 3:00 AM Points: 2,816, Visits: 1,593
 Yes, and apparently each space shuttle launch expected at least 6000 components to fail but was still designed to work.On my list of things not to think about is precisely how fast a piece of metal moves inside a motor-bike engine when it's between your legs
Post #1192977
 Posted Wednesday, October 19, 2011 11:04 AM
 SSCommitted Group: General Forum Members Last Login: Tuesday, January 15, 2013 11:11 AM Points: 1,945, Visits: 2,782
 I think you got trapped in teh procedural mindset. I would use a look up table with DECIMAL(s, 0) columns so i can get the range I need. Ther is one for 1 to 23! at http://membres.multimania.fr/rsirdey/facttabl.htmNow, we can apply a little algebra in a CASE expression instead of brute force: CREATE FUNCTION Perm(@n DECIMAL, @r DECIMAL)RETURNS DECIMAL (s,0)ASRETURN CASE WHEN @r = (0, @n) THEN 1.0 WHEN @r = 1.0 THEN @n THEN (SELECT fact FROM Factrorials WHERE @f = @n) / (SELECT fact FROM Factrorials WHERE @f = (@n-@r) ELSE CAST (NULL AS DECIMALs,0)) END; Books in Celko Series for Morgan-Kaufmann PublishingAnalytics and OLAP in SQL Data and Databases: Concepts in Practice Data, Measurements and Standards in SQLSQL for SmartiesSQL Programming Style SQL Puzzles and Answers Thinking in SetsTrees and Hierarchies in SQL
Post #1193052
 Posted Wednesday, October 19, 2011 12:17 PM
 SSCrazy Group: General Forum Members Last Login: Yesterday @ 3:00 AM Points: 2,816, Visits: 1,593
 Joe, I should have remembered that. I think one of your books mentioned storing a calendar table rather than trying to workout calendar maths on the fly.It is so easy to forget that storing a few thousand records for utility sets costs next to nothing but delivers one hell of a lot of utility
Post #1193120
 Posted Wednesday, October 19, 2011 1:34 PM
 Grasshopper Group: General Forum Members Last Login: Wednesday, May 29, 2013 11:18 AM Points: 10, Visits: 51
 Thanks for the great article. It reminds me of why when I used to fly airplanes my instructor kept telling me that the probability of an engine failure in a twin engine plane was twice as high as a single... of course you still had one engine running in a twin. do it right, or do it over and over, it's up to you
Post #1193190
 Posted Wednesday, October 19, 2011 3:10 PM
 Valued Member Group: General Forum Members Last Login: Wednesday, November 27, 2013 9:32 AM Points: 52, Visits: 377
 Don't you also need to make sure that @n <> @r so you don't divide by 0? And @r <> 0 either.
Post #1193255

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