Running error

[Seisstudnet]

Hello.
This is my first time using specfem3d and I get the following error when running it:

Program received signal SIGFPE: Floating-point exception - erroneous arithmetic operation.
Backtrace for this error:
#0 0x7fa494747f0f in ???
#1 0x43a2a8 in compute_forces_viscoelastic_
at src/specfem3D/compute_forces_viscoelastic.F90:682
#2 0x4280a9 in compute_forces_viscoelastic_calling_
at src/specfem3D/compute_forces_viscoelastic_calling_routine.F90:125
#3 0x4c676e in iterate_time_
at src/specfem3D/iterate_time.F90:279
#4 0x403473 in xspecfem3d
at src/specfem3D/specfem3D.F90:414
#5 0x403473 in main
at src/specfem3D/specfem3D.F90:365

What is the cause of this error? Is it a mesh problem or a source problem? What should I do to solve this error?

Thanks!

[danielpeter]

check your DT setting...

[Seisstudnet]

check your DT setting...

Thank you for your reply. I will check DT setting.

[Seisstudnet]

check your DT setting...

Hi, I would also like to ask you about this error. I checked my DT setting and it is less than ‘Maximum suggested time step’(like this).
*** Minimum period resolved = 0.584337354
*** Maximum suggested time step = 8.54999991E-04

*** for DT : 5.0000000000000001E-004
*** Max stability for wave velocities = 0.291652054

But I also have the same error.

Program received signal SIGFPE: Floating-point exception - erroneous arithmetic operation.
Backtrace for this error:
#0 0x7fa494747f0f in ???
#1 0x43a2a8 in compute_forces_viscoelastic_
at src/specfem3D/compute_forces_viscoelastic.F90:682
#2 0x4280a9 in compute_forces_viscoelastic_calling_
at src/specfem3D/compute_forces_viscoelastic_calling_routine.F90:125
#3 0x4c676e in iterate_time_
at src/specfem3D/iterate_time.F90:279
#4 0x403473 in xspecfem3d
at src/specfem3D/specfem3D.F90:414
#5 0x403473 in main
at src/specfem3D/specfem3D.F90:365

Why? What should I do next to solve it?

[danielpeter]

your DT is probably still too big. the outputted suggestion is only a rough estimate. in particular, if you have distorted elements, then a stable DT can be much smaller than the estimate.

to observe if the simulation blows up, you can set in DATA/Par_file:

NTSTEP_BETWEEN_OUTPUT_INFO   = 1

and check in OUTPUT_FILES/output_solver.txt if the maximum norm blows up:

..
 Time step #            5
..
 Max norm displacement vector U in all slices (m) =    2.24574184    
..

this will overflow the range for floating-point values and trigger the floating-point exception you see in your error message.

either choose a smaller DT in your Par_file, or re-mesh and make sure you create a mesh with more regular hexahedral elements.

[Seisstudnet]

your DT is probably still too big. the outputted suggestion is only a rough estimate. in particular, if you have distorted elements, then a stable DT can be much smaller than the estimate.

to observe if the simulation blows up, you can set in DATA/Par_file:

NTSTEP_BETWEEN_OUTPUT_INFO   = 1

and check in OUTPUT_FILES/output_solver.txt if the maximum norm blows up:

..
 Time step #            5
..
 Max norm displacement vector U in all slices (m) =    2.24574184    
..

this will overflow the range for floating-point values and trigger the floating-point exception you see in your error message.

either choose a smaller DT in your Par_file, or re-mesh and make sure you create a mesh with more regular hexahedral elements.

Thank you very much!! I'll try what you said.