http://www.k-wave.org/forum/topic/implementation-of-the-the-function-fitpowerlawparamsmulti Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 13:21:52 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/implementation-of-the-the-function-fitpowerlawparamsmulti#post-6917 Tue, 25 Jun 2019 08:59:12 +0000 Bradley Treeby 6917@http://www.k-wave.org/forum/ <p>Hi Gabrielle,</p> <p>This function gives absorption values that are correct at the reference frequency. In this case, the actual value of <code>y_ref</code> doesn't matter (I usually choose 2), provided that the absorption at <code>f_ref</code> match that expected by <code>a0</code> and <code>y</code>. The function automatically takes into account the actual absorption behaviour, including for highly absorbing media.</p> <p>Hope that helps,</p> <p>Brad </p> http://www.k-wave.org/forum/topic/implementation-of-the-the-function-fitpowerlawparamsmulti#post-6814 Sat, 30 Mar 2019 02:04:55 +0000 Gabrielle 6814@http://www.k-wave.org/forum/ <p>Hi,</p> <p>Thank you for such a wonderful toolbox!</p> <p>Recently I found the unreleased function <code>fitPowerLawParamsMulti</code> from the forum to solve the smallness approximation problem. </p> <p>I tried this function for a skull case with attenuation coefficient varies from 0 to 20 dB/cm and I assumed a constant power law exponent 2.0. It seems that this fitting function does not adjust the attenuation coefficient when ref_y is chosen as 2.0. </p> <p>Then I changed the ref_y to 1.5, the adjusted values from this function were smaller than original data. But when I check the paper "Modeling power law absorption and dispersion in viscoelastic solids using a split-field and the fractional Laplacian", the figure 2(a) shows that the fitting function will give higher values as the original absorption will underestimate the absorption.</p> <p>Another concern is that does this function only correct the values for moderate \omega\tau values? what about the case when \omega\tau&gt;&gt;1 ?</p> <p>many thanks,<br /> Gabrielle </p>