E-LETTER on Systems, Control, and Signal Processing ISSUE No. 3 (revised). Jan.27, 1987 Editors: Bradley W. Dickinson Dept. of Electrical Engineering Princeton University Princeton, NJ 08544 bradley@ivy.princeton.edu or {seismo, allegra}!princeton!ivy!bradley Eduardo D. Sontag Dept. of Mathematics Rutgers University New Brunswick, NJ 08903 sontag@fermat.rutgers.edu Welcome to the third issue of the E-LETTER. We remind you that items for posting can be emailed to either of the editors. Back issues of the newsletter can be requested from sontag@fermat.rutgers.edu. ---------------------------------------------------------------------- ADDITIONS TO MAILING LIST The following are additions to the mailing list which was included with the previous issue. An up-to-date copy of the complete list can be obtained from sontag@fermat.rutgers.edu. As usual, you may have to adjust the format depending on your mailer. Here we mixed uucp, csnet, and arpanet formats. tempo@itopoli.bitnet (Roberto Tempo) mtmarsh%weizmann.bitnet@wiscvm.wisc.edu (Marshall Slemrod) sagar%watale.waterloo.edu@relay.cs.net (M. Vidyasagar) irp%eeadfa.adfa.oz@seismo.css.gov (Ian Petersen) f1tannen@umn-ee-vax (Allen Tannenbaum) cobb%wiscmse.bitnet@wiscvm.wisc.edu (Dan Cobb) f1kharg@umn-ee-vax (Pramod Khargonekar) crowley@afsc-hq.arpa (Jim Crowley) wiscvm.wisc.edu!VKCHAW01%ULKYVX.BITNET (Vipin Chawla) mtarts%weizmann.bitnet@wiscvm.wisc.edu (Zvi Artstein) barmish%wiscmse.bitnet@wiscvm.wisc.edu (Bob Barmish) vastolak@csv.rpi.edu (Ken Vastola) sousa@utcsri.CSNET (Elvino Sousa) act%eeadfa.oz@SEISMO.CSS.GOV (A.C. Tsoi) irp@eeadfa.ee.adfa.oz.csnet (Ian Petersen) grossman@cartan.berkeley.edu (Robert Grossman) allegra!homxb!waffle (John Zavgren) reza@eecs.milw.wisc.edu lorilee@ll.arpa (Lori Jeromin) ganesh@rice.edu (Chidambar Ganesh) wongpw@isl.stanford.edu (Ping Wah Wong) per@wisdom.bitnet (Per Gutman) virag%cod@nosc.ARPA (David E. Virag) dlj@rice (Doug Jones) mcrmim@mcgill-vision.uucp (Sean Meyn) nps-cs.arpa!therrien (C.W. Therrien) allegra!homxb!dah (David Hoeflin) zabs@uicsl.csl.uiuc.edu (Serena Zabin) freddy%techsel.bitnet@wiscvm.arpa (Freddy Bruckstein) allegra!moss!nosc!humu!islenet!aloha1!kuh (Tony Kuh) shermanp@ecn.purdue.edu (Peter Sherman) safonov%arthur@usc-ecl.arpa (Mike Safonov) thobe@ee.ucla.edu (Glenn E. Thobe) ucsbcsl!sierra!gersho@berkeley.edu (Allen Gersho) allegra!rayssd!uriecl!vaccaro (Rick Vaccaro) irp@eeadfa.ee.adfa.oz (Ian Petersen) adam%TECHSEL.BITNET@WISCVM.WISC.EDU (Adam Shwartz) bardavid%TECHSEL.BITNET@WISCVM.WISC.EDU (I. Bar David) heymann%TECHSEL.BITNET@WISCVM.WISC.EDU (M. Heymann) izidor%TECHSEL.BITNET@WISCVM.WISC.EDU (I. Gertner) jz%TECHSEL.BITNET@WISCVM.WISC.EDU (J. Ziv) zeevi%TECHSEL.BITNET@WISCVM.WISC.EDU (Y. Zeevi) malah%TECHSEL.BITNET@WISCVM.WISC.EDU (D. Malah) sshlomo%TECHSEL.BITNET@WISCVM.WISC.EDU (S. Shitz) #dpstan%wmmvs.bitnet@wiscvm.wisc.edu (David Stanford) (Warning: above address seems to cause mailer problems!) New address for Ezio Biglieri: biglieri%itopoli.bitnet@wiscvm.wisc.edu New address for Wing Wong: allegra!hocus!wsw --------------------------------------------------------------------- ---------------------------------------------------------------------- ITEM FROM mattern@mb.ecn.purdue.edu (Duane L Mattern) We request your reaction to an ELECTRONIC NEWSGROUP for the discussion of Mathematical System Theory, Control Theory, and Signal Processing on a daily basis ('net.control'?). Typically this type of newsgroup is accessed through "rn" or "readnews". Articles could be posted using "Pnews". We would like a "show of electronic hands" to see how much interest there is in such a newsgroup; who would access it on a daily basis; whether your students are interested; and your general comments on the idea. Possible discussion might be on a particular paper, derivation, proof, or practical utility of an idea. Take for example the discussions about the usefulness of adaptive control between Rohrs and Astrom at the CDC Conferences in the early `80's. The specific subject matter would be controlled by the newsgroup users. A summary of the responses will be posted in the next EMSCS Newsletter. Please email your response to: ARPA:mattern@ecn.purdue.edu UUCP:ihnp4!inuxc!pur-ee!mattern ---------------------------------------------------------------------- ---------------------------------------------------------------------- CONFERENCE ANNOUNCEMENTS ---------------------------------------------------------------------- WORKSHOP ON SVD AND SIGNAL PROCESSING Sept.21-23, 1987, Grenoble, France. Summary by 15 march 87 to K.Jainandunsing Dept.of Electrical Engineering Delft Univ.of Technology room 16.23, Mekelweg 4 2628 CD Delft, The Netherlands ---------------------------------------------------------------------- 30th MIDWEST SYMP.CIRCUITS AND SYSTEMS Aug.17-18,1987, Syracuse, NY. Summary by 1 April 1987. Info from JABBOUR@SUVM.BITNET (K.Jabbour,ECE,Syracuse Univ.) ---------------------------------------------------------------------- OPTIMIZATION DAYS 87 May 13-15,1987, Montreal. Too late for summary (31 Jan). Info from E.Galperin Mathematiques et Informatique Univ.de Quebec a Montreal C.P.8888 Succ."A", Montreal, Quebec H3C 3P8 CANADA ---------------------------------------------------------------------- APPLIED MOTION CONTROL June 16-18,1987, Minneapolis. Too late for summary (1 Feb). Info from F.N.Baley EE, U.of Minnesota Minneapolis, MN 55455 (612)625-7808 ---------------------------------------------------------------------- ADVANCES IN COMMUNTCATION AND CONTROL SYSTEMS June 18-20,1987, Washington DC Info from A.B.Aries,COMCON Conferences, 4 park Ave, Suite 9D, NY, NY 10016. ---------------------------------------------------------------------- COMPUTERS AND COMMUNICATIONS TECHNOLOGY TOWARD 2000 (IEEE Region 10 Conference) August 26-28,1987, Seoul, (South) Korea. Abstract by 1 Mar 87 to C.K.Un Electrical Engineering Korea Advanced Inst.of Science and Technology P.O.Box 150 Chongyangni, Seoul, Korea. ---------------------------------------------------------------------- ---------------------------------------------------------------------- REMINDER: The new Journal MATHEMATICS OF CONTROL, SIGNALS, AND SYSTEMS is soliciting papers for publication. MCSS will be published by Springer Verlag, with the first issue due later this year. Details about the call for papers can be found in issue #2 of this newsletter, or from the newsletter editors. ---------------------------------------------------------------------- ---------------------------------------------------------------------- PAPER ABSTRACT: A Bisection Method for Measuring the Distance of a Stable Matrix to the Unstable Matrices Ralph Byers Department of Mathematics North Carolina State University @ Raleigh Raleigh, North Carolina 27695-8205 We describe a bisection method to determine the 2-norm and Frobenius norm distance from a given matrix A to the nearest matrix B with an eigenvalue on the imaginary axis. If A is stable in the sense that its eigenvalues lie in the open left half plane, then this distance measures "how nearly unstable" A is. Each step provides either a rigorous upper bound or a rigorous lower bound on the distance. A few bisection steps can bracket the distance within an order of magnitude. Bisection avoids the difficulties associated with nonlinear minimization techniques and the occasional failures associated with heuristic estimates. We show how the method might be used to estimate the distance to the nearest matrix with an eigenvalue on the unit circle. ---------------------------------------------------------------------- -----------------------------------.----------------------------------