id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
3118	Convergence issues on nonlinear equations not involving der()	Francesco Casella	Willi Braun	"Please consider the {{{ThermoPower.Test.WaterComponents.TestValves}}}. It takes 11 seconds to simulate in OMC and 0.12 seconds in Dymola, with {{{+cseCall}}} active.

Turning on {{{LOG_NLS_V}}} reveals the following behaviour:
- at time 3.0000 the NLS requires 137 iterations to converge,
  which probably points to badly chosen scaling factors or tolerances
- the main solver takes a step to 3.008
- the NLS now tries for 147 iterations, then it keeps trying doing
  other things for a long time, then eventually gives up
- the main solver steps back to 3.00000004, NLS converges quickly
- the main solver steps to 3.008, this time the convergence is 
  very fast
- the simulation proceeds normally

Bottom line 1: at time 3.000 there are probably too many iterations.

Bottom line 2: the first attempt at time 3.008 should have probably been aborted earlier, retrying a shorter step."	defect	accepted	high		Backend	trunk			Vitalij Ruge Lennart Ochel