Paul van Wamelen on Wed, 28 Aug 2002 01:01:55 -0500 (CDT) |
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bug? |
Dear all, The following is strange but at least understandable: ? exp(10^-300) %2 = 1.000000000000000000000000000 ? %-1 %3 = 1.000000000000000000000000000 E-300 ? % - 10^-300 %4 = 1.34971959 E-329 So exp of very small numbers are computed to large precision (I assume because it is possible!) But then cos should work the same way, but it doesn't: ? cos(10^-300) %5 = 1.000000000000000000000000000 ? %-1 %6 = -4.999999999999999999708086868 E-601 well sort of, but that isn't .5 to relative precision 28. It looks worse if you up the precision: ? default(realprecision,100) realprecision = 105 significant digits (100 digits displayed) ? cos(10^-300) - (1 - 10^-600/2) %11 = 2.91913131511413537189539175501010675755770891175910936852001807591773586414884430473814008517840 E-620 Shouldn't this be about 10^-700? I'm using GP/PARI CALCULATOR Version 2.1.1 (released) UltraSparc (MicroSparc kernel) 32-bit version (readline disabled, extended help available) but I believe this behaviour is VERY old. Sincerely, Paul van Wamelen