Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!usc!ucsd!ucbvax!agate!shelby!msi.umn.edu!noc.MR.NET!gacvx2.gac.edu!hhdist From: john%solvint@orstcs.UUCP Newsgroups: comp.sys.handhelds Subject: RE: Eigenvalues Message-ID: <9012201714.AA26392@CS.ORST.EDU> Date: 20 Dec 90 16:51:17 GMT Lines: 43 To: handhelds@gac.edu Return-path: <@cse.ogi.edu:orstcs!solvint!john@cse.ogi.edu> In-reply-to: ; from "gac.edu!handhelds" at Dec19, 90 7:04 pm To: handhelds@gac.edu Mailer: Elm [revision: 64.9] > Someone posted a message containing the program > \<> (where I = Identity matrix) > for finding the characteristic polynomial of a matrrix A. > I can't make it work because the 48 doesn't seem to permit > symbolic entries in arrayse, as was also the case with the 28s > Can someone give me the reference to this message? > Thanks...jim_wendel@ub.cc.umich.edu or jwendel@isdmnl.wr.usgs.gov > > Symbollic entries in arrays is not the point. One uses this program by making it the current SOLVER equation, putting a square array in 'A', the square identity in 'I' and solving for 'L', the eigenvalue. This program looks like it was taken from the "Easy Course in Using the HP-28S" where it was used to solve for the eigenvalues of matrix 'A', but since the 28 doesn't have the lambda character, L was used instead. To use it to find the characteristic polynomial of [[ 1 2 ][ 3 2 ]], do the following: \<< A I * - DET \>> [lshift] [SOLVE] [STEQ] [SOLVR] [[ 1 2 ][ 3 2 ]] [A] [[ 1 0 ][ 0 1 ]] [I] -100 [L] @ as a guess [lshift] [L] ==> L: -1 100 [L] @ as a guess [lshift] [L] ==> L: 4 To create the polynomial from these, subtract each from T and multiply: 'T' SWAP - SWAP 'T' SWAP - * This gives '(T+1)*(T-4). Expanding: EXPAN EXPAN COLCT gives '-4+T^2-3*T' -- John W. Loux | Solve and Integrate Corp solvint!john@orstcs.cs.orst.edu | PO Box 1928 john@solvint.uucp | Corvallis, OR 97339-1928 | (503) 754-1207