id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
3732	Segmentation fault at zero mass flow rate	Michael Wetter	somebody	"The following example gives a segmentation fault:

Run
{{{
export OPENMODELICALIBRARY=`pwd`:/usr/lib/omlibrary
omc +d=nogen,initialization,backenddaeinfo,discreteinfo,stateselection openmod.mos
}}}
with `openmod.mos` containing
{{{
loadModel(Modelica, {""3.2.1""});
getErrorString();
loadModel(Buildings); getErrorString();

simulate(Buildings.Fluid.HeatExchangers.Examples.DryEffectivenessNTU); getErrorString();
}}}


The output is
{{{
record SimulationResult
    resultFile = """",
    simulationOptions = ""startTime = 0.0, stopTime = 360.0, numberOfIntervals = 500, tolerance = 1e-06, method = 'dassl', fileNamePrefix = 'Buildings.Fluid.HeatExchangers.Examples.DryEffectivenessNTU', options = '', outputFormat = 'mat', variableFilter = '.*', cflags = '', simflags = ''"",
    messages = ""Simulation execution failed for model: Buildings.Fluid.HeatExchangers.Examples.DryEffectivenessNTU
assert            | debug   | division by zero at time 0.72, (a=0) / (b=0), where divisor b expression is: hexPar.m2_flow
assert            | debug   | division by zero at time 0, (a=0) / (b=0), where divisor b expression is: hexPar.m2_flow

Limited backtrace at point of segmentation fault
/lib/x86_64-linux-gnu/libpthread.so.0(+0x10340)[0x7f4c7d71c340]
/lib/x86_64-linux-gnu/libc.so.6(_longjmp+0x10)[0x7f4c7d37db40]
/lib/x86_64-linux-gnu/libpthread.so.0(+0xed69)[0x7f4c7d71ad69]
/usr/lib/x86_64-linux-gnu/omc/libSimulationRuntimeC.so(throwStreamPrintWithEquationIndexes+0xfc)[0x7f4c7e9d39fc]
/usr/lib/x86_64-linux-gnu/omc/libSimulationRuntimeC.so(+0x29a77)[0x7f4c7e9d3a77]
/home/mwetter/proj/ldrd/bie/modeling/github/lbl-srg/modelica-buildings/Buildings.Fluid.HeatExchangers.Examples.DryEffectivenessNTU(Buildings_Fluid_HeatExchangers_Examples_DryEffectivenessNTU_eqFunction_1139+0x18d)[0x4782bd]
/home/mwetter/proj/ldrd/bie/modeling/github/lbl-srg/modelica-buildings/Buildings.Fluid.HeatExchangers.Examples.DryEffectivenessNTU(Buildings_Fluid_HeatExchangers_Examples_DryEffectivenessNTU_functionDAE+0x8e2)[0x486ab2]
/usr/lib/x86_64-linux-gnu/omc/libSimulationRuntimeC.so(updateDiscreteSystem+0x8d)[0x7f4c7ea0cbdd]
/home/mwetter/proj/ldrd/bie/modeling/github/lbl-srg/modelica-buildings/Buildings.Fluid.HeatExchangers.Examples.DryEffectivenessNTU[0x46a744]
/home/mwetter/proj/ldrd/bie/modeling/github/lbl-srg/modelica-buildings/Buildings.Fluid.HeatExchangers.Examples.DryEffectivenessNTU(Buildings_Fluid_HeatExchangers_Examples_DryEffectivenessNTU_performSimulation+0x574)[0x469c24]
/usr/lib/x86_64-linux-gnu/omc/libSimulationRuntimeC.so(solver_main+0x17c)[0x7f4c7ea1433c]
/usr/lib/x86_64-linux-gnu/omc/libSimulationRuntimeC.so(callSolver+0x2c9)[0x7f4c7ea36f49]
/usr/lib/x86_64-linux-gnu/omc/libSimulationRuntimeC.so(startNonInteractiveSimulation+0x5c8)[0x7f4c7ea359c8]
/usr/lib/x86_64-linux-gnu/omc/libSimulationRuntimeC.so(_main_SimulationRuntime+0x70)[0x7f4c7ea37fa0]
/home/mwetter/proj/ldrd/bie/modeling/github/lbl-srg/modelica-buildings/Buildings.Fluid.HeatExchangers.Examples.DryEffectivenessNTU(main+0x1f7)[0x487667]
Segmentation fault (core dumped)
... [omitted]
}}}

Setting `POut.k=101225` avoids zero mass flow rate, in which case there is no segmentation fault.

The model is from the latest version of the `master` branch of `Buildings`, e.g., https://github.com/lbl-srg/modelica-buildings/commit/d0841740172f2812891be5693a9cc4450e1327b8"	defect	closed	high	Future	*unknown*	v1.9.4-dev-nightly	worksforme