http://www.k-wave.org/forum/topic/the-wave-wrapping-caused-by-computed-spatial-derivatives-via-fft Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 03:13:15 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/the-wave-wrapping-caused-by-computed-spatial-derivatives-via-fft#post-5923 Thu, 11 May 2017 09:24:23 +0000 ZHANG Fan 5923@http://www.k-wave.org/forum/ <p>Hi Laurent,</p> <p>I understand now. Thank you very much for your help!</p> <p>Best,<br /> Fan </p> http://www.k-wave.org/forum/topic/the-wave-wrapping-caused-by-computed-spatial-derivatives-via-fft#post-5913 Mon, 08 May 2017 07:17:33 +0000 g.schober@skz.de 5913@http://www.k-wave.org/forum/ <p>Hi Fan,</p> <p>the 'wave wrapping' happens due to the fact that the FFT needs peridiocity from the subject that is computed. So one of the edges is connected to the other one on the other end and the same is to say for every other edge.</p> <p>Best regards<br /> Laurent </p> http://www.k-wave.org/forum/topic/the-wave-wrapping-caused-by-computed-spatial-derivatives-via-fft#post-5912 Sun, 07 May 2017 14:21:59 +0000 ZHANG Fan 5912@http://www.k-wave.org/forum/ <p>Hi everyone,</p> <p>For PS or k-space methods, the computation of the spatial derivatives via the FFT causes waves leaving one side of the domain to reappear at the opposite side. This wave wrapping can be avoided by implementing an absorbing boundary condition known as a perfectly matched layer.</p> <p>I did observed this phenomenon called 'wave wrapping', but I can't understand how FFT causes it. Could anyone help explain it? Thanks in advance.</p> <p>Best,<br /> Fan </p>