alpha_+ envelope of E1b (in-process) = [15.4256608821 +/- 3.11e-11]
alpha_+ in uv_constants.json         = 15.425661  [consistent]
k=800: 3779.4

sweep [650,899]: 78 non-positive
first positive k = 728   positive block contiguous: True
min over positive block = 27.6508  (at k = 728)
non-positive k: [650,727]  contiguous: True
endpoints: crit(650)=-3271.0806, crit(899)=10046.1138