<html><body><div style="font-family: arial,helvetica,sans-serif; font-size: 12pt; color: #000000"><hr id="zwchr" data-marker="__DIVIDER__"><div data-marker="__HEADERS__"><b>From: </b>"Audrey Nichols" <anichols@jlab.org><br><b>Sent: </b>Friday, April 15, 2016 8:00:00 AM<br><b>Subject: </b>Re: [Accelerator_staff] Accelerator Seminar: 4/15/16 - Jingwei Hu<br></div><div><br></div><div data-marker="__QUOTED_TEXT__"><div style="font-family: tahoma,new york,times,serif; font-size: 12pt; color: #000000" data-mce-style="font-family: tahoma,new york,times,serif; font-size: 12pt; color: #000000;"><div>Reminder!</div><br><br><hr id="zwchr"><div><b>From: </b>"Audrey Barron" <anichols@jlab.org><br><b>To: </b>"acc staff" <acc_staff@jlab.org>, "FEL Staff" <fel-staff@jlab.org><br><b>Cc: </b>"Jingwei Hu" <jingweihu@purdue.edu><br><b>Sent: </b>Thursday, April 7, 2016 4:00:00 PM<br><b>Subject: </b>[Accelerator_staff] Accelerator Seminar: 4/15/16 - Jingwei Hu<br></div><br><div><div style="font-family: tahoma,new york,times,serif; font-size: 12pt; color: #000000" data-mce-style="font-family: tahoma,new york,times,serif; font-size: 12pt; color: #000000;"><div><span style="color: rgb(0, 0, 0);" data-mce-style="color: #000000;">ACCELERATOR SEMINAR</span><br></div><br><div><span style="color: rgb(0, 0, 0);" data-mce-style="color: #000000;">A Fast Butterfly Algorithm for Generalized Radon Transforms </span><br></div><br><div><span style="color: rgb(0, 0, 0);" data-mce-style="color: #000000;">Jingwei Hu</span><br></div><div><span style="color: rgb(0, 0, 0);" data-mce-style="color: #000000;">Perdue University</span><br></div><br><div><p style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;" data-mce-style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="font-size: 12pt; color: rgb(0, 0, 0);" data-mce-style="font-size: 12pt; color: #000000;"><span style="font-family: Arial;" data-mce-style="font-family: Arial;">The fast butterfly algorithm, as originally proposed by </span><span style="font-family: Arial;" data-mce-style="font-family: Arial;">Candes</span><span style="font-family: Arial;" data-mce-style="font-family: Arial;">, </span><span style="font-family: Arial;" data-mce-style="font-family: Arial;">Demanet</span><span style="font-family: Arial;" data-mce-style="font-family: Arial;">, and Ying, is used to accelerate the $N$-body interaction with oscillatory kernel: $u(x)=\</span><span style="font-family: Arial;" data-mce-style="font-family: Arial;">sum_y</span><span style="font-family: Arial;" data-mce-style="font-family: Arial;"> e^{2\pi </span><span style="font-family: Arial;" data-mce-style="font-family: Arial;">i</span><span style="font-family: Arial;" data-mce-style="font-family: Arial;"> \phi(</span><span style="font-family: Arial;" data-mce-style="font-family: Arial;">x,y</span><span style="font-family: Arial;" data-mce-style="font-family: Arial;">)} g(y)$. In this talk, we consider its application to the Radon transform --- an integral transform taken along arbitrary parameterized sets of smooth curves/surfaces whose application includes imaging, wave/Maxwell equations, and retarded effect in the relativistic E-M fields. The basic idea to reformulate the transform as an oscillatory integral operator and to construct a </span><span style="font-family: Arial;" data-mce-style="font-family: Arial;">blockwise</span><span style="font-family: Arial;" data-mce-style="font-family: Arial;"> low-rank approximation of the kernel function. For 2D problem, the algorithm runs in complexity $O(N^2\log N)$ as apposed to $O(N^3)$ of the direct time-domain integration.</span></span></p><p style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;" data-mce-style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="font-size: 16pt; font-family: Arial; color: rgb(0, 0, 0);" data-mce-style="font-size: 16pt; font-family: Arial; color: #000000;"><br></span></p><p style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;" data-mce-style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="font-size: 12pt; font-family: Arial; color: rgb(0, 0, 0);" data-mce-style="font-size: 12pt; font-family: Arial; color: #000000;">Friday, April 15, 2016<br></span></p><p style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;" data-mce-style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="font-size: 12pt; font-family: Arial; color: rgb(0, 0, 0);" data-mce-style="font-size: 12pt; font-family: Arial; color: #000000;">11:00 a.m.<br></span></p><p style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;" data-mce-style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="font-size: 12pt; font-family: Arial; color: rgb(0, 0, 0);" data-mce-style="font-size: 12pt; font-family: Arial; color: #000000;">CEBAF Center, Room L102<br></span></p><p style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;" data-mce-style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="font-size: 12pt; font-family: Arial; color: rgb(0, 0, 0);" data-mce-style="font-size: 12pt; font-family: Arial; color: #000000;"><br></span></p><p style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;" data-mce-style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="font-size: 12pt; font-family: Arial; color: black;" data-mce-style="font-size: 12pt; font-family: Arial; color: black;">Seminar archives are found here: <a href="https://www.jlab.org/accel/seminars.html" target="_blank" data-mce-href="https://www.jlab.org/accel/seminars.html">https://www.jlab.org/accel/seminars.html</a><br></span></p><p style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;" data-mce-style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="font-size: 16.0pt; font-family: Arial; color: black; language: en-US;" data-mce-style="font-size: 16.0pt; font-family: Arial; color: black; language: en-US;"><br></span></p></div><br><div id="c527d5bf-234f-450e-be05-77753629e03f"><div>------<br><b><span style="font-size: small;" data-mce-style="font-size: small;">Audrey N. Barron</span></b><br><span style="font-size: small;" data-mce-style="font-size: small;">Administrative Assistant</span><br><span style="font-size: small;" data-mce-style="font-size: small;">Center for Advanced Studies of Accelerators</span><br><span style="font-size: small;" data-mce-style="font-size: small;">Jefferson Lab</span><br><span style="font-size: small;" data-mce-style="font-size: small;">757-269-7327</span><br><span style="font-size: small;" data-mce-style="font-size: small;"><a href="http://<a href="mailto:anichols@jlab.org">anichols@jlab.org</a>Email Me</a> " target="_blank" data-mce-href="http://<a href="mailto:anichols@jlab.org">anichols@jlab.org</a>Email Me</a> ">anichols@jlab.org</a></span> / <span style="font-size: small;" data-mce-style="font-size: small;"><a href="http://www.jlab.org" target="_blank" data-mce-href="http://www.jlab.org">www.jlab.org</a></span> <br><br><img src="cid:385434c8fc58f7b3d43cb80d6533fcca500e1cae@zimbra" style="border: 0px none;" data-mce-src="cid:385434c8fc58f7b3d43cb80d6533fcca500e1cae@zimbra" data-mce-style="border: 0px none;"><br></div></div></div><br>_______________________________________________<br>Accelerator_staff mailing list<br>Accelerator_staff@jlab.org<br>https://mailman.jlab.org/mailman/listinfo/accelerator_staff<br></div></div><br>_______________________________________________<br>Accelerator_staff mailing list<br>Accelerator_staff@jlab.org<br>https://mailman.jlab.org/mailman/listinfo/accelerator_staff<br></div></div></body></html>