http://www.k-wave.org/forum/topic/slightly-different-results-between-kspacefirstorder2d-and-kspacefirstorder2dg Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 01:49:48 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/slightly-different-results-between-kspacefirstorder2d-and-kspacefirstorder2dg#post-8249 Wed, 21 Jul 2021 14:31:14 +0000 Bradley Treeby 8249@http://www.k-wave.org/forum/ <p>Hi Neo,</p> <p>If you normalise to the maximum value in the grid, the differences between the C++ and MATLAB codes should be on the order of single precision (e.g., 1e-5 to 1e-6). We have a test code that runs a large number of comparisons under different scenarios.</p> <p>There are a number of options that aren't supported in the C++/CUDA codes, and unfortunately there is no currently no warning that these are being ignored. I will address this with the next release.</p> <p>In the interim, some of the non-supported options are:<br /> - Anything related to display or movies (there is no display)<br /> - Cartesian sensor mask<br /> - <code>medium.alpha_mode</code><br /> - <code>medium.alpha_filter</code><br /> - <code>medium.alpha_sign</code><br /> - <code>sensor.directivity_angle</code><br /> - <code>sensor.directivity_size</code><br /> - <code>sensor.directivity_pattern</code></p> <p>Hope that helps,</p> <p>Brad </p> http://www.k-wave.org/forum/topic/slightly-different-results-between-kspacefirstorder2d-and-kspacefirstorder2dg#post-8223 Wed, 23 Jun 2021 16:13:14 +0000 Neo 8223@http://www.k-wave.org/forum/ <p>I have uploaded some Matlab Files so that you can easily check these differences yourself.<br /> You can download these files here:<br /> <a href="https://ruhr-uni-bochum.sciebo.de/s/LxtleUpNbREHSWi" rel="nofollow">https://ruhr-uni-bochum.sciebo.de/s/LxtleUpNbREHSWi</a><br /> The password is: kwave13</p> <p>Just download the folder "kWave_OptimizedSimFct_Debugging", add all subfolders to the active Matlab path and run the script "MainScript_SimFctDebugging.m". The Script automatically loads the already simulated data that is stored in the folder "SimulationData" and visualizes the RF data.</p> <p>I suspect that the difference is caused by numerical inaccuracies/noise, that is different for the optimized and non-optimized functions. Or is the simulation in the optimized simulation functions implemented differently than in the Matlab version? I would really like to know if these differences are normal or not and what actually causes them.</p> <p>The manual says on page 58:<br /> "To test whether the CPU/GPU codes are working correctly, open the “Diagnostic Ultrasound Simultion, Simulating Ultrasound Beam Patterns Example”, replace kspaceFirstOrder3D<br /> with kspaceFirstOrder3DC or kspaceFirstOrder3DG, then run the simulation and verify<br /> the outputs are the same."<br /> If the difference in simulation results is normal, this section of text causes some confusion </p> http://www.k-wave.org/forum/topic/slightly-different-results-between-kspacefirstorder2d-and-kspacefirstorder2dg#post-8222 Mon, 21 Jun 2021 16:28:19 +0000 Neo 8222@http://www.k-wave.org/forum/ <p>Hi,<br /> I have a quick question about the new kspaceFirstOrder2DG Function which was published with the 1.3 release of kwave. Until now I used kspaceFirstOrder2D with DataCast set to gpuArray-single. To speed up simulations I want to switch to the optimized simulation function and thus tried the kspaceFirstOrder2DG function. I downloaded the compiled binary fdiles and put them into the binary folder of the kwave toolbox.<br /> I wanted to be sure, that both functions return the same simulation result but actually this is not the case. When I compare the simulation results, I get and RMSE of 0.0379 and a global maximum absolut difference of 0.3797.<br /> The deviation is small and the reconstructed b-Mode images look the same, but I wonder if this difference between the simulation results is normal?</p> <p>The manual says that "not all simulation options are currently supported by the CPU/GPU code. The sensor mask must be given as either a binary matrix or (...). All display parameters are ignored". Are there other restrictions which one should know, when using the optimized code?</p> <p>(I get the same difference in data when I use kspaceFirstOrder2D with DataCast set to Single and kspaceFirstOrder2DC) </p>