I changed the solver !
The issue was : we created an y[ ... ] containing each differential fields. dealing with scalar and vectoral equation was ok (I was using an index vector inside) but adding matrix was very messy.
Recoding the part made :
Solver easier to read and understand
Any time of data compatible
Access to state variable possible
Solver faster (3.5s before, 3s now for 10000 iteration of a GK)
I changed the solver ! The issue was : we created an y[ ... ] containing each differential fields. dealing with scalar and vectoral equation was ok (I was using an index vector inside) but adding matrix was very messy.
Recoding the part made :