Running: ./testmodel.py --libraries=/home/hudson/saved_omc/libraries/.openmodelica/libraries/ --ompython_omhome=/usr Buildings_8_Buildings.Fluid.Actuators.Dampers.Examples.VAVBoxExponential.conf.json loadFile("/home/hudson/saved_omc/libraries/.openmodelica/libraries/ModelicaServices 4.0.0+maint.om/package.mo", uses=false) loadFile("/home/hudson/saved_omc/libraries/.openmodelica/libraries/Complex 4.0.0+maint.om/package.mo", uses=false) loadFile("/home/hudson/saved_omc/libraries/.openmodelica/libraries/Modelica 3.2.3+maint.om/package.mo", uses=false) loadFile("/home/hudson/saved_omc/libraries/.openmodelica/libraries/Buildings 8.1.4-maint.8.1.x/package.mo", uses=false) Using package Buildings with version 8.1.4 (/home/hudson/saved_omc/libraries/.openmodelica/libraries/Buildings 8.1.4-maint.8.1.x/package.mo) Using package Modelica with version 3.2.3 (/home/hudson/saved_omc/libraries/.openmodelica/libraries/Modelica 3.2.3+maint.om/package.mo) Using package Complex with version 4.0.0 (/home/hudson/saved_omc/libraries/.openmodelica/libraries/Complex 4.0.0+maint.om/package.mo) Using package ModelicaServices with version 4.0.0 (/home/hudson/saved_omc/libraries/.openmodelica/libraries/ModelicaServices 4.0.0+maint.om/package.mo) Running command: "" <> buildModelFMU(Buildings.Fluid.Actuators.Dampers.Examples.VAVBoxExponential,fileNamePrefix="Buildings_8_Buildings_Fluid_Actuators_Dampers_Examples_VAVBoxExponential",fmuType="me",version="2.0",platforms={"static"}) "" <> buildModelFMU(Buildings.Fluid.Actuators.Dampers.Examples.VAVBoxExponential,fileNamePrefix="Buildings_8_Buildings_Fluid_Actuators_Dampers_Examples_VAVBoxExponential",fmuType="me",version="2.0",platforms={"static"}) Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/ModelicaServices 4.0.0+maint.om/package.mo): time 0.000893/0.000893, allocations: 90.75 kB / 15.06 MB, free: 1.098 MB / 14.72 MB Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/Complex 4.0.0+maint.om/package.mo): time 0.001094/0.001094, allocations: 172.7 kB / 15.95 MB, free: 208 kB / 14.72 MB Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/Modelica 3.2.3+maint.om/package.mo): time 1.688/1.688, allocations: 205.4 MB / 222.1 MB, free: 5.473 MB / 174.1 MB Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/Buildings 8.1.4-maint.8.1.x/package.mo): time 1.848/1.848, allocations: 292.7 MB / 0.5499 GB, free: 14.53 MB / 462.1 MB Notification: Modelica requested package Complex of version 3.2.3. Complex 4.0.0 is used instead which states that it is fully compatible without conversion script needed. Notification: Modelica requested package ModelicaServices of version 3.2.3. ModelicaServices 4.0.0 is used instead which states that it is fully compatible without conversion script needed. Notification: Performance of FrontEnd - loaded program: time 0.0005672/0.0005672, allocations: 14.16 kB / 0.6738 GB, free: 26.02 MB / 0.5294 GB Notification: Performance of FrontEnd - Absyn->SCode: time 0.2764/0.277, allocations: 116.3 MB / 0.7874 GB, free: 11.83 MB / 0.6075 GB Notification: Performance of NFInst.instantiate(Buildings.Fluid.Actuators.Dampers.Examples.VAVBoxExponential): time 0.8177/1.095, allocations: 158.9 MB / 0.9425 GB, free: 5.398 MB / 0.7169 GB Notification: Performance of NFInst.instExpressions: time 0.0107/1.105, allocations: 5.811 MB / 0.9482 GB, free: 5.207 MB / 0.7169 GB Notification: Performance of NFInst.updateImplicitVariability: time 0.001062/1.107, allocations: 19.22 kB / 0.9482 GB, free: 5.207 MB / 0.7169 GB Notification: Performance of NFTyping.typeComponents: time 0.001166/1.108, allocations: 298.6 kB / 0.9485 GB, free: 5.18 MB / 0.7169 GB Notification: Performance of NFTyping.typeBindings: time 0.00274/1.11, allocations: 0.7864 MB / 0.9493 GB, free: 4.98 MB / 0.7169 GB Notification: Performance of NFTyping.typeClassSections: time 0.009435/1.12, allocations: 1.953 MB / 0.9512 GB, free: 4.801 MB / 0.7169 GB Notification: Performance of NFFlatten.flatten: time 0.003628/1.124, allocations: 1.774 MB / 0.9529 GB, free: 4.539 MB / 0.7169 GB Notification: Performance of NFFlatten.resolveConnections: time 0.001178/1.125, allocations: 0.4995 MB / 0.9534 GB, free: 4.449 MB / 0.7169 GB Notification: Performance of NFEvalConstants.evaluate: time 0.001832/1.127, allocations: 0.6725 MB / 0.9541 GB, free: 4.305 MB / 0.7169 GB Notification: Performance of NFSimplifyModel.simplify: time 0.0007709/1.127, allocations: 0.5244 MB / 0.9546 GB, free: 4.199 MB / 0.7169 GB Notification: Performance of NFPackage.collectConstants: time 0.0001124/1.128, allocations: 34.66 kB / 0.9546 GB, free: 4.199 MB / 0.7169 GB Notification: Performance of NFFlatten.collectFunctions: time 0.002158/1.13, allocations: 0.7806 MB / 0.9554 GB, free: 4.129 MB / 0.7169 GB Notification: Performance of NFScalarize.scalarize: time 0.0003496/1.13, allocations: 244.7 kB / 0.9556 GB, free: 4.094 MB / 0.7169 GB Notification: Performance of NFVerifyModel.verify: time 0.0006308/1.131, allocations: 168.8 kB / 0.9558 GB, free: 20.04 MB / 0.7325 GB Notification: Performance of NFConvertDAE.convert: time 0.001715/1.132, allocations: 0.981 MB / 0.9567 GB, free: 19.95 MB / 0.7325 GB Notification: Performance of FrontEnd - DAE generated: time 6.863e-06/1.132, allocations: 0 / 0.9567 GB, free: 19.95 MB / 0.7325 GB Notification: Performance of FrontEnd: time 2.334e-06/1.132, allocations: 1.406 kB / 0.9567 GB, free: 19.95 MB / 0.7325 GB Notification: Performance of Transformations before backend: time 1.276e-05/1.132, allocations: 0 / 0.9567 GB, free: 19.95 MB / 0.7325 GB Notification: Model statistics after passing the front-end and creating the data structures used by the back-end: * Number of equations: 91 * Number of variables: 91 Notification: Performance of Generate backend data structure: time 0.002643/1.135, allocations: 1.189 MB / 0.9579 GB, free: 19.23 MB / 0.7325 GB Notification: Performance of prepare preOptimizeDAE: time 4.85e-05/1.135, allocations: 13.27 kB / 0.9579 GB, free: 19.23 MB / 0.7325 GB Notification: Performance of preOpt introduceOutputAliases (simulation): time 9.918e-05/1.135, allocations: 78.36 kB / 0.958 GB, free: 19.19 MB / 0.7325 GB Notification: Performance of preOpt normalInlineFunction (simulation): time 0.0006073/1.136, allocations: 137.5 kB / 0.9581 GB, free: 19.14 MB / 0.7325 GB Notification: Performance of preOpt evaluateParameters (simulation): time 0.001303/1.137, allocations: 0.7103 MB / 0.9588 GB, free: 18.85 MB / 0.7325 GB Notification: Performance of preOpt simplifyIfEquations (simulation): time 5.085e-05/1.137, allocations: 39.28 kB / 0.9588 GB, free: 18.85 MB / 0.7325 GB Notification: Performance of preOpt expandDerOperator (simulation): time 9.62e-05/1.137, allocations: 49.42 kB / 0.9589 GB, free: 18.85 MB / 0.7325 GB Notification: Performance of preOpt clockPartitioning (simulation): time 0.0009778/1.138, allocations: 0.506 MB / 0.9594 GB, free: 18.72 MB / 0.7325 GB Notification: Performance of preOpt findStateOrder (simulation): time 1.483e-05/1.138, allocations: 0 / 0.9594 GB, free: 18.72 MB / 0.7325 GB Notification: Performance of preOpt replaceEdgeChange (simulation): time 4.625e-05/1.138, allocations: 20.11 kB / 0.9594 GB, free: 18.71 MB / 0.7325 GB Notification: Performance of preOpt inlineArrayEqn (simulation): time 1.642e-05/1.138, allocations: 12.86 kB / 0.9594 GB, free: 18.71 MB / 0.7325 GB Notification: Performance of preOpt removeEqualRHS (simulation): time 0.0007633/1.139, allocations: 357.6 kB / 0.9598 GB, free: 18.7 MB / 0.7325 GB Warning: The model contains alias variables with redundant start and/or conflicting nominal values. It is recommended to resolve the conflicts, because otherwise the system could be hard to solve. To print the conflicting alias sets and the chosen candidates please use -d=aliasConflicts. Notification: Performance of preOpt removeSimpleEquations (simulation): time 0.003215/1.142, allocations: 1.938 MB / 0.9617 GB, free: 17.73 MB / 0.7325 GB Notification: Performance of preOpt comSubExp (simulation): time 0.0007213/1.143, allocations: 346.7 kB / 0.962 GB, free: 17.7 MB / 0.7325 GB Notification: Performance of preOpt resolveLoops (simulation): time 0.0003632/1.144, allocations: 170.1 kB / 0.9621 GB, free: 17.69 MB / 0.7325 GB Notification: Performance of preOpt evalFunc (simulation): time 0.0003264/1.144, allocations: 194.4 kB / 0.9623 GB, free: 17.5 MB / 0.7325 GB Notification: Performance of preOpt encapsulateWhenConditions (simulation): time 3.699e-05/1.144, allocations: 39.38 kB / 0.9624 GB, free: 17.46 MB / 0.7325 GB Notification: Performance of pre-optimization done (n=26): time 1.413e-06/1.144, allocations: 1.219 kB / 0.9624 GB, free: 17.46 MB / 0.7325 GB Notification: Performance of matching and sorting (n=26): time 0.002012/1.146, allocations: 0.7055 MB / 0.9631 GB, free: 17.25 MB / 0.7325 GB Notification: Performance of inlineWhenForInitialization (initialization): time 0.0001165/1.146, allocations: 212.7 kB / 0.9633 GB, free: 17 MB / 0.7325 GB Notification: Performance of selectInitializationVariablesDAE (initialization): time 0.001531/1.148, allocations: 0.9177 MB / 0.9642 GB, free: 16.87 MB / 0.7325 GB Notification: Performance of collectPreVariables (initialization): time 6.162e-05/1.148, allocations: 33.45 kB / 0.9642 GB, free: 16.84 MB / 0.7325 GB Notification: Performance of collectInitialEqns (initialization): time 0.0003623/1.148, allocations: 365.8 kB / 0.9645 GB, free: 16.72 MB / 0.7325 GB Notification: Performance of collectInitialBindings (initialization): time 8.92e-05/1.148, allocations: 92.48 kB / 0.9646 GB, free: 16.66 MB / 0.7325 GB Notification: Performance of simplifyInitialFunctions (initialization): time 2.17e-05/1.148, allocations: 7.156 kB / 0.9646 GB, free: 16.66 MB / 0.7325 GB Notification: Performance of setup shared object (initialization): time 0.0001588/1.148, allocations: 318.2 kB / 0.9649 GB, free: 16.36 MB / 0.7325 GB Notification: Performance of preBalanceInitialSystem (initialization): time 0.0003636/1.149, allocations: 157.1 kB / 0.9651 GB, free: 16.36 MB / 0.7325 GB Notification: Performance of partitionIndependentBlocks (initialization): time 0.0005323/1.149, allocations: 369.9 kB / 0.9654 GB, free: 16.13 MB / 0.7325 GB Notification: Performance of analyzeInitialSystem (initialization): time 0.0004235/1.15, allocations: 201.7 kB / 0.9656 GB, free: 16.11 MB / 0.7325 GB Notification: Performance of solveInitialSystemEqSystem (initialization): time 5.741e-06/1.15, allocations: 5.312 kB / 0.9656 GB, free: 16.11 MB / 0.7325 GB Notification: Performance of matching and sorting (n=38) (initialization): time 0.001346/1.151, allocations: 0.5388 MB / 0.9662 GB, free: 16.01 MB / 0.7325 GB Notification: Performance of prepare postOptimizeDAE: time 0.0001253/1.151, allocations: 109.1 kB / 0.9663 GB, free: 15.9 MB / 0.7325 GB Notification: Performance of postOpt simplifyComplexFunction (initialization): time 3.05e-05/1.151, allocations: 4.953 kB / 0.9663 GB, free: 15.9 MB / 0.7325 GB Notification: Performance of postOpt tearingSystem (initialization): time 0.0003614/1.152, allocations: 58.61 kB / 0.9663 GB, free: 15.89 MB / 0.7325 GB Notification: Performance of postOpt solveSimpleEquations (initialization): time 0.000539/1.152, allocations: 100.7 kB / 0.9664 GB, free: 15.88 MB / 0.7325 GB Notification: Performance of postOpt calculateStrongComponentJacobians (initialization): time 0.0007617/1.153, allocations: 1.153 MB / 0.9676 GB, free: 14.77 MB / 0.7325 GB Notification: Performance of postOpt simplifyAllExpressions (initialization): time 0.0009697/1.154, allocations: 120.2 kB / 0.9677 GB, free: 14.74 MB / 0.7325 GB Notification: Performance of postOpt collapseArrayExpressions (initialization): time 4.354e-05/1.154, allocations: 11.67 kB / 0.9677 GB, free: 14.74 MB / 0.7325 GB Notification: Performance of prepare postOptimizeDAE: time 1.072e-05/1.154, allocations: 7.984 kB / 0.9677 GB, free: 14.74 MB / 0.7325 GB Notification: Performance of postOpt replaceHomotopyWithSimplified (initialization): time 0.0008883/1.155, allocations: 427.2 kB / 0.9681 GB, free: 14.71 MB / 0.7325 GB Notification: Performance of postOpt simplifyComplexFunction (initialization): time 1.437e-05/1.155, allocations: 5.469 kB / 0.9681 GB, free: 14.71 MB / 0.7325 GB Notification: Performance of postOpt tearingSystem (initialization): time 0.0001343/1.155, allocations: 35.45 kB / 0.9681 GB, free: 14.7 MB / 0.7325 GB Notification: Performance of postOpt solveSimpleEquations (initialization): time 0.0003582/1.155, allocations: 77.44 kB / 0.9682 GB, free: 14.7 MB / 0.7325 GB Notification: Performance of postOpt calculateStrongComponentJacobians (initialization): time 0.001336/1.157, allocations: 1.484 MB / 0.9697 GB, free: 13.35 MB / 0.7325 GB Notification: Performance of postOpt simplifyAllExpressions (initialization): time 0.00088/1.158, allocations: 107.9 kB / 0.9698 GB, free: 13.32 MB / 0.7325 GB Notification: Performance of postOpt collapseArrayExpressions (initialization): time 3.108e-05/1.158, allocations: 12 kB / 0.9698 GB, free: 13.32 MB / 0.7325 GB Notification: Model statistics after passing the back-end for initialization: * Number of independent subsystems: 3 * Number of states: 0 () * Number of discrete variables: 0 () * Number of discrete states: 0 () * Number of clocked states: 0 () * Top-level inputs: 0 Notification: Strong component statistics for initialization (31): * Single equations (assignments): 25 * Array equations: 2 * Algorithm blocks: 0 * Record equations: 2 * When equations: 0 * If-equations: 0 * Equation systems (linear and non-linear blocks): 1 * Torn equation systems: 1 * Mixed (continuous/discrete) equation systems: 0 Notification: Equation system details: * Constant Jacobian: 0 * Linear Jacobian (size,density): 0 * Non-linear Jacobian: 1 {1} * Without analytic Jacobian: 0 Notification: Torn system details for strict tearing set: * Linear torn systems: 0 * Non-linear torn systems: 1 {1 3} Notification: Performance of prepare postOptimizeDAE: time 0.0004572/1.158, allocations: 290.5 kB / 0.97 GB, free: 13.13 MB / 0.7325 GB Notification: Performance of postOpt lateInlineFunction (simulation): time 0.0001417/1.158, allocations: 77.19 kB / 0.9701 GB, free: 13.09 MB / 0.7325 GB Notification: Performance of postOpt wrapFunctionCalls (simulation): time 0.001081/1.159, allocations: 479.2 kB / 0.9706 GB, free: 13.01 MB / 0.7325 GB Notification: Performance of postOpt inlineArrayEqn (simulation): time 4.599e-06/1.159, allocations: 3.469 kB / 0.9706 GB, free: 13.01 MB / 0.7325 GB Notification: Performance of postOpt constantLinearSystem (simulation): time 1.794e-06/1.159, allocations: 0 / 0.9706 GB, free: 13.01 MB / 0.7325 GB Notification: Performance of postOpt simplifysemiLinear (simulation): time 7.854e-06/1.159, allocations: 2.531 kB / 0.9706 GB, free: 13.01 MB / 0.7325 GB Notification: Performance of postOpt removeSimpleEquations (simulation): time 0.002178/1.162, allocations: 1.226 MB / 0.9718 GB, free: 12.61 MB / 0.7325 GB Notification: Performance of postOpt simplifyComplexFunction (simulation): time 5.831e-06/1.162, allocations: 4 kB / 0.9718 GB, free: 12.61 MB / 0.7325 GB Notification: Performance of postOpt solveSimpleEquations (simulation): time 0.0003371/1.162, allocations: 64.22 kB / 0.9718 GB, free: 12.61 MB / 0.7325 GB Notification: Performance of postOpt tearingSystem (simulation): time 0.0001072/1.162, allocations: 40 kB / 0.9719 GB, free: 12.59 MB / 0.7325 GB Notification: Performance of postOpt inputDerivativesUsed (simulation): time 3.086e-05/1.162, allocations: 12.41 kB / 0.9719 GB, free: 12.59 MB / 0.7325 GB Notification: Performance of postOpt calculateStrongComponentJacobians (simulation): time 0.0006576/1.163, allocations: 1.154 MB / 0.973 GB, free: 11.48 MB / 0.7325 GB Notification: Performance of postOpt calculateStateSetsJacobians (simulation): time 2.995e-06/1.163, allocations: 3.531 kB / 0.973 GB, free: 11.48 MB / 0.7325 GB Notification: Performance of postOpt symbolicJacobian (simulation): time 0.001193/1.164, allocations: 0.7448 MB / 0.9738 GB, free: 11.23 MB / 0.7325 GB Notification: Performance of postOpt removeConstants (simulation): time 0.0003174/1.164, allocations: 210.8 kB / 0.974 GB, free: 11.09 MB / 0.7325 GB Notification: Performance of postOpt simplifyTimeIndepFuncCalls (simulation): time 0.0001019/1.164, allocations: 9.938 kB / 0.974 GB, free: 11.09 MB / 0.7325 GB Notification: Performance of postOpt simplifyAllExpressions (simulation): time 0.0006278/1.165, allocations: 60.22 kB / 0.974 GB, free: 11.08 MB / 0.7325 GB Notification: Performance of postOpt findZeroCrossings (simulation): time 7.732e-05/1.165, allocations: 31.89 kB / 0.974 GB, free: 11.07 MB / 0.7325 GB Notification: Performance of postOpt collapseArrayExpressions (simulation): time 2.3e-05/1.165, allocations: 10.8 kB / 0.9741 GB, free: 11.07 MB / 0.7325 GB Notification: Performance of sorting global known variables: time 0.0008852/1.166, allocations: 0.6587 MB / 0.9747 GB, free: 10.98 MB / 0.7325 GB Notification: Performance of sort global known variables: time 3.2e-07/1.166, allocations: 0 / 0.9747 GB, free: 10.98 MB / 0.7325 GB Notification: Performance of remove unused functions: time 0.001272/1.167, allocations: 350.2 kB / 0.975 GB, free: 10.95 MB / 0.7325 GB Notification: Model statistics after passing the back-end for simulation: * Number of independent subsystems: 7 * Number of states: 4 (dam.filter.x[1],dam.filter.x[2],vav.filter.x[1],vav.filter.x[2]) * Number of discrete variables: 0 () * Number of discrete states: 0 () * Number of clocked states: 0 () * Top-level inputs: 0 Notification: Strong component statistics for simulation (25): * Single equations (assignments): 23 * Array equations: 0 * Algorithm blocks: 0 * Record equations: 0 * When equations: 0 * If-equations: 0 * Equation systems (linear and non-linear blocks): 1 * Torn equation systems: 1 * Mixed (continuous/discrete) equation systems: 0 Notification: Equation system details: * Constant Jacobian: 0 * Linear Jacobian (size,density): 0 * Non-linear Jacobian: 1 {1} * Without analytic Jacobian: 0 Notification: Torn system details for strict tearing set: * Linear torn systems: 0 * Non-linear torn systems: 1 {1 3} Notification: Performance of Backend phase and start with SimCode phase: time 0.002176/1.17, allocations: 1.421 MB / 0.9764 GB, free: 10.14 MB / 0.7325 GB Notification: Performance of simCode: created initialization part: time 0.001908/1.172, allocations: 0.8201 MB / 0.9772 GB, free: 9.848 MB / 0.7325 GB Notification: Performance of simCode: created event and clocks part: time 3.867e-06/1.172, allocations: 4 kB / 0.9772 GB, free: 9.844 MB / 0.7325 GB Notification: Performance of simCode: created simulation system equations: time 0.0004092/1.172, allocations: 188.9 kB / 0.9774 GB, free: 9.809 MB / 0.7325 GB Notification: Performance of simCode: created of all other equations (e.g. parameter, nominal, assert, etc): time 0.001661/1.174, allocations: 330.2 kB / 0.9777 GB, free: 9.695 MB / 0.7325 GB Notification: Performance of simCode: created linear, non-linear and system jacobian parts: time 0.008444/1.182, allocations: 4.846 MB / 0.9825 GB, free: 7.641 MB / 0.7325 GB Notification: Performance of simCode: some other stuff during SimCode phase: time 0.0006337/1.183, allocations: 0.969 MB / 0.9834 GB, free: 6.828 MB / 0.7325 GB Notification: Performance of simCode: alias equations: time 0.000874/1.184, allocations: 184 kB / 0.9836 GB, free: 6.742 MB / 0.7325 GB Notification: Performance of simCode: all other stuff during SimCode phase: time 0.0004159/1.184, allocations: 280.7 kB / 0.9838 GB, free: 6.711 MB / 0.7325 GB Notification: Performance of SimCode: time 1.252e-06/1.184, allocations: 0 / 0.9838 GB, free: 6.711 MB / 0.7325 GB Notification: Performance of buildModelFMU: Generate the FMI files: time 0.04743/1.232, allocations: 21.75 MB / 1.005 GB, free: 12.39 MB / 0.7481 GB Notification: Performance of buildModelFMU: configured platform static using cached values: time 0.0002144/1.232, allocations: 271.6 kB / 1.005 GB, free: 12.03 MB / 0.7481 GB Notification: Performance of buildModelFMU: Generate platform static: time 2.403/3.635, allocations: 0 / 1.005 GB, free: 12.03 MB / 0.7481 GB (rm -f Buildings_8_Buildings.Fluid.Actuators.Dampers.Examples.VAVBoxExponential.pipe ; mkfifo Buildings_8_Buildings.Fluid.Actuators.Dampers.Examples.VAVBoxExponential.pipe ; head -c 1048576 < Buildings_8_Buildings.Fluid.Actuators.Dampers.Examples.VAVBoxExponential.pipe >> ../files/Buildings_8_Buildings.Fluid.Actuators.Dampers.Examples.VAVBoxExponential.sim & /home/hudson/saved_omc/OMSimulator/install/linux/bin/OMSimulator --tempDir=temp_Buildings_8_Buildings_Fluid_Actuators_Dampers_Examples_VAVBoxExponential_fmu --startTime=0 --stopTime=240 --timeout=50 --tolerance=1e-06 Buildings_8_Buildings_Fluid_Actuators_Dampers_Examples_VAVBoxExponential.fmu > Buildings_8_Buildings.Fluid.Actuators.Dampers.Examples.VAVBoxExponential.pipe 2>&1) Environment - environmentSimulation: