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AnHeuermannclaude
AnHeuermann
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claude
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Don't call CVode with an interval it cannot integrate (#1621)
doStepCVODE accumulates end_time while the event times come from the FMU, so an event landing on the last ULP before end_time leaves time < end_time true with nothing integrable in between: time = 0.080000000000000001665 clock tick reported by the FMU end_time = 0.080000000000000015543 accumulated by the loop tout = min(tnext, end_time) = end_time gap = 1.39e-17 CVode rejects such an interval with CV_TOO_CLOSE, but only on the first call after a re-init - which is exactly the call following every event - so the whole simulation fails there. Skip the call and take end_time as reached, using CVode's own too-close test. Reproduced by simulation/clockedStepBoundary: a Modelica.Clocked FMU whose tick times are exact (k * period) against a communication step of 0.008, which fails at t = 0.08 without this change. Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
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‎src/OMSimulatorLib/SystemSC.cpp‎

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@@ -881,6 +881,15 @@ oms_status_enu_t oms::SystemSC::doStepCVODE()
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{
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const fmi3Float64 tout = std::min(tnext, end_time);
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// CVode rejects an interval it cannot tell apart from zero (CV_TOO_CLOSE)
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// There is nothing left to integrate in it; assume end_time is reached.
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if (tout - time < 2.0 * SUN_UNIT_ROUNDOFF * std::max(std::fabs(time), std::fabs(tout)))
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{
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logDebug("CVode: skipping degenerate interval " + std::to_string(time) + " -> " + std::to_string(tout));
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time = end_time;
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break;
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}
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logDebug("CVode: " + std::to_string(time) + " -> " + std::to_string(tout));
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for (size_t j=0, k=0; j < fmus.size(); ++j)
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for (size_t i=0; i < nStates[j]; ++i, ++k)

‎testsuite/tests/resources/CMakeLists.txt‎

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@@ -12,6 +12,7 @@ set(OM_OMS_TESTSUITE_RESOURCES_FMUS
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${CMAKE_CURRENT_SOURCE_DIR}/B
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${CMAKE_CURRENT_SOURCE_DIR}/BouncingBall
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${CMAKE_CURRENT_SOURCE_DIR}/BouncingBall3
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${CMAKE_CURRENT_SOURCE_DIR}/ClockedStepBoundary
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${CMAKE_CURRENT_SOURCE_DIR}/Dahlquist
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${CMAKE_CURRENT_SOURCE_DIR}/Dahlquist3
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${CMAKE_CURRENT_SOURCE_DIR}/DualMassOscillator.System1

‎testsuite/tests/resources/ClockedStepBoundary.mos‎

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// Regenerates testsuite/resources/ClockedStepBoundary.
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//
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// A clocked model: Modelica.Clocked drives it from periodic clocks whose tick
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// times are computed exactly (k * period), while a master stepping the FMU
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// accumulates its own communication points. The two disagree by an ULP once the
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// accumulated end of a communication step lands just past a tick, which is what
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// the clockedStepBoundary test exercises.
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loadModel(Modelica, {"4.0.0"}); getErrorString();
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buildModelFMU(Modelica.Clocked.Examples.CascadeControlledDrive.AbsoluteClocks, version="2.0", fmuType="me", fileNamePrefix="ClockedStepBoundary", platforms={"x86_64-linux-gnu docker run multiarch/crossbuild","x86_64-w64-mingw32 docker run multiarch/crossbuild"}); getErrorString();
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system("zip -qd ClockedStepBoundary.fmu sources/* && unzip -o ClockedStepBoundary.fmu -d ClockedStepBoundary/");

‎testsuite/tests/resources/ClockedStepBoundary/binaries/linux64/ClockedStepBoundary.so‎

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‎testsuite/tests/resources/ClockedStepBoundary/documentation/index.html‎

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<h1>Modelica.Clocked.Examples.CascadeControlledDrive.AbsoluteClocks</h1>
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<p> <i>Drive with clocked cascade controller where all partitions are defined with exact (integer) clock that need to be compatible to each other</i> </p>
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<h4> <u> Information </u> </h4><html>
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<p>
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Cascade control drive with discrete-time controller where two
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periodic clock with absolute periods are defined and
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are associated to
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the corresponding controller partitions.
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The super-sampling factor of block "super" is derived by
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clock inference.
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</p>
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</html>
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<h4> <u> Revisions </u> </h4>

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