1function test27 2%TEST27 test cs_qr, cs_utsolve, cs_qrsol 3% 4% Example: 5% test27 6% See also: testall 7 8% Copyright 2006-2012, Timothy A. Davis, http://www.suitesparse.com 9 10clear functions 11rand ('state', 0) ; 12 13Prob = ssget ('HB/ibm32') ; 14A = Prob.A ; 15A = A (1:10,:) ; 16[m n] = size (A) ; 17 18[V,Beta,p,R,q] = cs_qr (A') ; 19 20b = rand (m,1) ; 21 22Rm = R (1:m,1:m) ; 23 24bq = b (q) ; 25rtbq = Rm' \ bq ; 26 27rt2 = cs_utsolve (Rm, bq) ; 28 29norm (rtbq - rt2) 30 31x = [rt2 ; zeros(n-m,1)] ; 32 33for k = m:-1:1 34 x = x - V(:,k) * (Beta (k) * (V (:,k)' * x)) ; 35end 36 37x (p) = x ; 38 39norm (A*x-b) 40 41x2 = cs_qrsol (A,b) ; 42 43norm (A*x2-b) 44norm (x-x2) 45