IDA/Analysis: Difference between revisions

Revision as of 13:13, 21 March 2015

This pages contains some notes on the analysis algorithm that is used in our IDA solver in ASCEND. Work in progress!

reanalyze_solver_lists, to update the rels/vars in the system system according to the WHENs
set the 'nonbasic' flag to zero for all normal variables, and to one for the independent variable ('x')
integrator_ida_check_vars, to check for differential variables that are not incident, downgrading 'differential' variables to algebraic variables if no derivative is present, and marking any...
integrator_ida_flag_rels
integrator_ida_sort_rels_and_vars
integrator_ida_create_lists
integrator_ida_check_diffindex (performs a series of hopefully unnecessary checks)
(there is some code commented out here to do with checking the structure of the system for structural singularity etc)
integrator_ida_check_index should tell the user if there is an index problem (perhaps we can apply automatic index reduction?)
some checks of the diffvars: do we have a single indep var, is the indep var what we expected it to be.
copy the list of observed vars (both continuous and discrete) into the integ data struct.

TODO complete this section.

The IDA integrator works a bit differently in the analysis phase to DOPRI5 and LSODE (it would be nice to be able to unify these things).

@@ Line 7: / Line 7: @@
 # '''<tt>integrator_ida_sort_rels_and_vars</tt>'''
 # '''<tt>integrator_ida_create_lists</tt>'''
-# '''<tt>integrator_ida_check_diffindex</tt>'''
+# '''<tt>integrator_ida_check_diffindex</tt>''' (performs a series of ''hopefully unnecessary'' checks)
 # (there is some code commented out here to do with checking the structure of the system for structural singularity etc)
 # '''<tt>integrator_ida_check_index</tt>''' should tell the user if there is an index problem (perhaps we can apply automatic index reduction?)