k-Wave

1. ouelletn
   

   Member
   Joined: May '13
   Posts: 18

   Based on calculations from the K-wave manual the simulation I am running requires an incredibly small time step to remain stable and prevent phase error(~e-11), I am currently having issues storing the matrix of transmit receive values and cannot find a way to store the values at certain time intervals, eg every 500 steps, in the k-wave code and documentation, I was wondering if one is available?

   Posted 10 years ago #

2. ouelletn
   

   Member
   Joined: May '13
   Posts: 18

   it appears that I have miscalculated that time step, although the question about storing data at intervals still stands, thanks.

   Posted 10 years ago #

3. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,640

   In the current code there is no way to only store the data at some of the time steps. However, that would be relatively easy to implement. For example, in the 3D MATLAB code, on line 979 change

   (t_index >= sensor.record_start_index)

   to

   (rem(t_index, save_step) == 0)

   where save_step is an integer which defines how often you want to save the data. Note that this modification would also need some changes to how num_recorded_time_points is defined in /private/kspaceFirstOrder_createStorageVariables.

   It is currently possible to set when the recording starts by defining sensor.record_start_index. This is useful if you're only interested in storing the wave-field after it reaches steady state (for example).

   Brad.

   Posted 10 years ago #

4. ouelletn
   

   Member
   Joined: May '13
   Posts: 18

   I have posted the changes I made below, in case anyone else needs to implement this.
   I changed kspaceFirstOrder2D line 886 to add the further condition
   && mod(t_index,save_step)==0

   and line 891 to
   file_index = floor(t_index/save_step) - sensor.record_start_index + 1

   I changed line 73 of /private/kspaceFirstOrder_createStorageVariables
   num_recorded_time_points = floor(kgrid.Nt/save_step) - sensor.record_start_index + 1;

   the final change I made was to add the input option using 'SaveFreq' to input_args by adding the following after line 739
   

   case 'SaveFreq'
      save_step = varargin{input_index + 1};

   also, thanks for the help.

   Posted 10 years ago #

5. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,640

   Glad you got it to work, and thanks for posting your code!

   Posted 10 years ago #

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