9
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Bug introduced in 10.0.1 and fixed in 12.0.0

Version 11.2.0.0 on MacBook Pro:

w[n_] := 2^(-1 + n) QPochhammer[-1, 3/2, n]
Print["Auto:     ", SumConvergence[w[n], n]]
Print["Ratio:    ", SumConvergence[w[n], n, Method -> "RatioTest"]]

Yields True and False respectively. Auto is apparently wrong as suggested by:

ListPlot[Log[Table[w[n], {n, 1, 100}]]]

and also by hand-calculating the ratio test.

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  • 3
    $\begingroup$ Seems to be also the case in 11.3 $\endgroup$ – chris Dec 16 '18 at 8:08
  • $\begingroup$ Perhaps, time to add "bugs" tag and header, and report to Wolfram, Inc. $\endgroup$ – bbgodfrey Dec 16 '18 at 18:32
  • $\begingroup$ How do I report it? $\endgroup$ – Paul R. Dec 17 '18 at 2:47
  • $\begingroup$ This also occurs in V10.0.1 on Mac OS X. Adding the bugs tag. $\endgroup$ – march Dec 17 '18 at 5:39
  • $\begingroup$ To report a bug. $\endgroup$ – march Dec 17 '18 at 5:46

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