# Bug in SumConvergence

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.

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