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IDProjectCategoryView StatusLast Update
0000549ascendintegratorpublic2012-04-24 08:04
Reporterjohn 
Assigned To 
PrioritynormalSeverityfeatureReproducibilityalways
Status newResolutionopen 
PlatformLinuxOSUbuntuOS Version12.04 LTS
Product Version0.9.8 
Target Version1.0Fixed in Version 
Summary0000549: IDA can't integrate constants
DescriptionThere is an important degenerate case that we can't currently support with the IDA integrator, and possibly other integrators too.

A model that simply aims to calculate integ(1*t, t) from 0 to 10 fails, because we can't integrate a constant (1).

The problem lies in the integration process, which doesn't add the integral variable unless it's explicitly present in the model equations.

Steps To ReproduceIn current trunk (changeset 4096) attempt to load the file models/test/ida/integ1.a4c.

After attempting to start the integration, ASCEND crashes with

ascend/integrator/integrator.c:283 (integrator_set_engine): Setting engine...
ascend/integrator/integrator.c:508 (integrator_analyse): Analysing integration system...
ascend/integrator/integrator.c:448 (integrator_find_indep_var): sys->x already set
ascend/integrator/integrator.c:525 (integrator_analyse): got 0 from integrator_find_indep_var
solvers/ida/idaanalyse.c:521 (integrator_ida_analyse): System contains a total of 0 bnds and 2 rels
solvers/ida/idaanalyse.c:524 (integrator_ida_analyse): Currently 2 rels active
solvers/ida/idaanalyse.c:530 (integrator_ida_analyse): After analysing WHENs, there are 2 rels active
solvers/ida/idaanalyse.c:129 (integrator_ida_check_vars): 'y' has a derivative present, so needs to be included in the system
solvers/ida/idaanalyse.c:130 (integrator_ida_check_vars): That var is active
solvers/ida/idaanalyse.c:214 (integrator_ida_flag_rels): Found 1 differential equations (so 1 algebraic)


PROGRAM FATAL ERROR: solvers/ida/idaanalyse.c:248:integrator_ida_sort_rels_and_vars: Assertion failed: ny1 == integ->n_y

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john

2012-04-21 03:27

administrator   ~0000871

See code/trunk/models/test/ida/integ1.a4c.

john

2012-04-24 08:04

administrator   ~0000877

Model code/trunk/models/solar/incident.a4c is affected by this bug.

Issue History

Date Modified Username Field Change
2012-04-20 06:53 john New Issue
2012-04-21 03:27 john Note Added: 0000871
2012-04-21 08:04 svn
2012-04-24 08:04 john Note Added: 0000877