Fix roundoff issue in SUNDIALS evolve() #4148
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ajnonaka
changed the title
ajnonaka
changed the title
WeiqunZhang
reviewed
Sep 12, 2024
Src/Base/AMReX_RKIntegrator.H
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| @@ -251,7 +251,8 @@ public: | |||
| for (int step_number = 0; step_number < BaseT::max_steps && !stop; ++step_number) | |||
| { | |||
| // Adjust step size to reach output time | |||
| if (time_out - time_current < dt) { | |||
| // protect against roundoff | |||
| if (std::abs(time_out - time_current - dt) <= 1.e5 * std::numeric_limits<amrex::Real>::epsilon() * std::abs(dt)) { | |||
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What if Real is float?
We could also do amrex::almostEqual(time_current+dt, time_out). almostEqual has an optional argument that can be used to fine tune what is considered almost equal.
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That sounds good, I'll test it.
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@WeiqunZhang how is this?
|
Any reasons why |
|
@WeiqunZhang fixed |
WeiqunZhang
approved these changes
Sep 17, 2024
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Summary
Fix a roundoff issue in the SUNDIALS evolve() function that caused the integrator to run a second time with a very tiny dt in a given time step.
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Checklist
The proposed changes: