Timeline for Roots of Whittaker W function
Current License: CC BY-SA 3.0
7 events
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| Apr 13, 2017 at 12:55 | history | edited | CommunityBot |
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| Nov 15, 2016 at 16:07 | comment | added | Michael E2 |
@Alex I'm not sure whether you're asking in general, but, in general, that can happen if the derivative is very large, or if there are significant rounding errors in computing the function, or maybe some other things. I usually get an warning message. The first thing I try is setting the AccuracyGoal explicitly and increasing WorkingPrecision to 3 to 10 times the accuracy goal. If raising WP doesn't get me closer, then I wonder what's special about the problem.
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| Nov 15, 2016 at 15:42 | comment | added | Alex | I see, thank you. One more question: I would like the precision of FindRoot to be say 100 decimal places. I tried setting WorkingPrecision to 200, which should automatically set PrecisionGoal and AccuracyGoal to 100 each. However, at the zeros returned by FindRoot the target function does not evaluate to a number as small as $10^{-100}$. Is it fixable? | |
| Nov 15, 2016 at 11:52 | comment | added | Michael E2 |
1*^-15 is Mathematica's shorthand "scientific notation." It means 1 * 10^-15.
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| Nov 15, 2016 at 4:37 | comment | added | Alex | One quick question: what's 1*^-15 in Abs[Im[#]] < 1*^-15? I don't understand the syntax. | |
| May 5, 2016 at 1:44 | vote | accept | Alex | ||
| Apr 28, 2016 at 3:00 | history | answered | Michael E2 | CC BY-SA 3.0 |