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seen Dec 16 at 20:29

Dec
4
comment Inverse of LogIntegral
Works great, thanks! I tweaked the WorkingPrecision and PrecisionGoal upward and all was good.
Dec
4
accepted Inverse of LogIntegral
Dec
4
comment Inverse of LogIntegral
@DanielLichtblau: Thanks. (Maybe that should be an answer.) Mathematica is still giving me answers I don't believe (say, integrating up to 10^200 giving an answer of 2*10^7 instead of < 0.1) but at this point it seems hopeless. At least it works for small numbers.
Dec
4
comment Inverse of LogIntegral
(The true answer should be about 0.01125, or 19 orders of magnitude smaller.)
Dec
4
comment Inverse of LogIntegral
@DanielLichtblau: That's not a sensible answer, though. The li^{-1}(x) > x (in fact ~ x log x), so the integral should be less than the integral of 1/x over the same region, which is about 4.6.
Dec
4
comment Inverse of LogIntegral
@Artes: With an NIntegrate::inumr error. I've edited in code.
Dec
4
revised Inverse of LogIntegral
expand, as requested
Dec
4
asked Inverse of LogIntegral
Aug
5
comment Use of Strassen's algorithm
@TysonWilliams: BLAS does use Strassen in DGEMMS*. But Daniel's description of why to avoid that algorithm for floating-point calculations is apt.
Jul
2
awarded  Curious
May
28
awarded  Nice Question
May
22
comment How do I get Mathematica to return a function call unevaluated?
Hah! So at least I wasn't too far off the mark, just careless. Thanks for pointing this out!
May
22
awarded  Yearling
May
22
comment How do I get Mathematica to return a function call unevaluated?
@gpap: What do you get for AlgebraicQ /@ {7, Pi, Pi + E, I}?
May
22
comment How do I get Mathematica to return a function call unevaluated?
@gpap: I can't imagine how, honestly. I mean, clearly that should work if I gave it a non-Real, but for a Real it should return Element[x, Algebraics] because that's what you're telling it to return. Very strange, I'd be interested to learn more about this case.
May
22
revised How do I get Mathematica to return a function call unevaluated?
final answer
May
22
revised How do I get Mathematica to return a function call unevaluated?
flesh out
May
22
accepted How do I get Mathematica to return a function call unevaluated?
May
22
comment How do I get Mathematica to return a function call unevaluated?
@m_goldberg: The built-in AlgebraicIntegerQ has precisely the same behavior I'm describing. (How could a function possibly guarantee to return True or False when the answer is not even known to mathematicians?)
May
22
revised How do I get Mathematica to return a function call unevaluated?
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