http://www.k-wave.org/forum/topic/silent-error-messages-because-isfield-on-user-defined-class-always-returns-false Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 11:19:39 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/silent-error-messages-because-isfield-on-user-defined-class-always-returns-false#post-7227 Wed, 12 Feb 2020 15:59:35 +0000 Bradley Treeby 7227@http://www.k-wave.org/forum/ <p>Hi Chris,</p> <p>Thanks for the tip - that's useful. We'll add it to the bug list.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/silent-error-messages-because-isfield-on-user-defined-class-always-returns-false#post-7197 Fri, 24 Jan 2020 00:09:44 +0000 ChrisBerk 7197@http://www.k-wave.org/forum/ <p>Hello,</p> <p>I think I've found a few places in the code where, due to this odd behavior of the function <code>isfield</code> which always returns false if called on a user defined class, a few error messages are silent. This mainly affects when <code>isfield</code> is used to check fields on a kwaveTransducer used as a sensor or source.</p> <p>More info on this behaviour here: <a href="https://uk.mathworks.com/matlabcentral/answers/94688-why-does-isfield-always-return-false-when-querying-a-user-defined-class-in-matlab-7-7-r2008b" rel="nofollow">https://uk.mathworks.com/matlabcentral/answers/94688-why-does-isfield-always-return-false-when-querying-a-user-defined-class-in-matlab-7-7-r2008b</a></p> <p>The places I've been able to locate where this results in actual behavioral changes are:</p> <p>- In kspaceFirstOrder3DC, there is a check for record_start_index that never succeeds, so the command line option isn't propogated<br /> - In kspaceFirstOrder_inputChecking, in the lines</p> <pre><code>% check that the transducer is only being used in forward mode if isfield(sensor, &#39;time_reversal_boundary_data&#39;) error(&#39;Transducer inputs not supported with time reversal.&#39;); end % check that sensor.record is not set if isfield(sensor, &#39;record&#39;) error(&#39;sensor.record cannot be set when using kWaveTransducer objects as the sensor.&#39;); end</code></pre> <p>the errors are never called even if the field is present.</p> <p>I've had a look through all of the other places that isfield is used, and I don't think there is any other shadowed behaviour, but it might be worth someone else taking a look as it is used a lot.</p> <p>Kind regards,<br /> Chris </p>