On Sat, 2014-06-28 at 03:42 -0700, Walter Bright via Digitalmars-d wrote: > On 6/28/2014 2:47 AM, francesco cattoglio wrote: > > When you need accuracy, 999 times out of 1000 you change the numerical > > technique, you don't just blindly upgrade the precision. > > I have experience doing numerical work? Upgrading the precision is the first > thing people try.
Nonetheless, algorithm and expression of algorithm are often more important. As proven by my Pi_Quadrature examples you can appear to have better results with greater precision, but actually the way the code operates is actually the core problem: the code I have written does not do things in the best way to achieve the best result as a given accuracy level.. […] > > Errors accumulate very rapidly and easily overwhelm the significance of the > answer. I wonder if programmers should only be allowed to use floating point number sin their code if they have studied numerical analysis? > > > Especially the numerical analysts themselves will pay that price. 64 bit > > HAS to > > be as fast as possible, if you want to be competitive when it comes to any > > kind > > of numerical work. > > Getting the wrong answer quickly is not useful when you're calculating the > stress levels in a part. […] > Again, I've done numerical programming in airframe design. The correct answer > is > what matters. You can accept wrong answers in graphics display algorithms, > but > not when designing critical parts. Or indeed when calculating anything to do with money. -- Russel. ============================================================================= Dr Russel Winder t: +44 20 7585 2200 voip: sip:[email protected] 41 Buckmaster Road m: +44 7770 465 077 xmpp: [email protected] London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder
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