Possibly you understand now why in Gaussian Elimination I chose to arbitrarily set the midpoint along the x-axis to zero and keep the numbers along the scale in fairly tight range, and perform the calcs in double precission ... yes ?
--- In [email protected], "Tom Tom" <[EMAIL PROTECTED]> wrote: > > So after further investigation. > > > I code loop in VBS double. Result is not the same than SUM, nor FOR. > So SUM or FOR are not exact, but they act not the same in rounding. I thing > the arythmetic order to calculate is not the same in FOR and in SUM so > rounding are different, so result are different. > But one or other, result is not accurate. > If I want to stay in AFL and I had to choose between SUM and FOR, wich one I > will go ? As they are both innacurate, SUM seems better ? > > > I test max/min number for AFL after reading the link from Paul : > http://en.wikipedia.org/wiki/IEEE_754 > > Code : > > ieee = -1e10; > _TRACE("IEEE:"+ ieee); // to show exponent > _TRACE("IEEE:"+ NumToStr(ieee,1.9) ); // to show innacurate digit > > And try after with : > ieee = 1e11; > > exponant should go from -126 to +127, but in our case : > ieee = 1e-10; -> result are infinite > ieee = 1e11; -> ok for direct trace, but with numtostr there is rounding and > do not use exponent notation > ieee = 1e39; -> result are infinite > > So my question, wy exponent go from -10 to 39 !? > And NumToStr(x,1.9), seems to send back rounding result. Cannot it send back > with exponent notation and no rounding like direct _trace ? > > Second, accuracy seems 7 digit, but it should be 6 digit ? (max number from > the mantisse is 2^23 - 1 = 8388607, that give 7 number so six digit sure). > Try: ieee = 99999981 > 7th digit is ok. 8th digit is wrong. > > So AB use wich encoding (not IEEE_754 ?) and difference between direct > _trace and _trace with NumToStr come from NumToStr wich make rounding for > big exponent ? > > Cheers, > Mich. > > _________________________________________________________________ > Windows Live Messenger sur i-modeĀ : dialoguez avec vos amis depuis votre > mobile comme sur PC ! http://mobile.live.fr/messenger/bouygues/ >
