id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
3681	calculateStrongComponentJacobians is slow and scales badly	Francesco Casella	Willi Braun	"The calculateStrongComponentJacobians function is slow and scales badly.

Run the attached test case. It contains N systems of 4 nonlinear equations, with 3 tearing variables each. These are the execution times reported on my pc for the calculateStrongComponentJacobians function applied to simulation equations

|| N || Time [s] ||
||100||0.77||
||400||4.8||
||1600||28||
||3200||78||

The time scales more than proportionally, which seems weird. As the algorithm calculates the jacobians of N completely independent systems, the time should be strictly proportional to N.

For large enough numbers of system, each one takes 25 ms to compute the derivatives, which seems a bit too much, given that the functions involved are almost linear and very easy to differentiate.

Last, but not least, if I try to improve the compilation time by adding the {{{--postOptModules-=calculateStrongComponentJacobians}}}, the function is executed anyway."	defect	closed	critical		Backend	v1.9.4-dev-nightly	fixed