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SUBROUTINE SGET36( RMAX, LMAX, NINFO, KNT, NIN )
* * -- LAPACK test routine (version 3.1) -- * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. * November 2006 * * .. Scalar Arguments .. INTEGER KNT, LMAX, NIN REAL RMAX * .. * .. Array Arguments .. INTEGER NINFO( 3 ) * .. * * Purpose * ======= * * SGET36 tests STREXC, a routine for moving blocks (either 1 by 1 or * 2 by 2) on the diagonal of a matrix in real Schur form. Thus, SLAEXC * computes an orthogonal matrix Q such that * * Q' * T1 * Q = T2 * * and where one of the diagonal blocks of T1 (the one at row IFST) has * been moved to position ILST. * * The test code verifies that the residual Q'*T1*Q-T2 is small, that T2 * is in Schur form, and that the final position of the IFST block is * ILST (within +-1). * * The test matrices are read from a file with logical unit number NIN. * * Arguments * ========== * * RMAX (output) REAL * Value of the largest test ratio. * * LMAX (output) INTEGER * Example number where largest test ratio achieved. * * NINFO (output) INTEGER array, dimension (3) * NINFO(J) is the number of examples where INFO=J. * * KNT (output) INTEGER * Total number of examples tested. * * NIN (input) INTEGER * Input logical unit number. * * ===================================================================== * * .. Parameters .. REAL ZERO, ONE PARAMETER ( ZERO = 0.0E0, ONE = 1.0E0 ) INTEGER LDT, LWORK PARAMETER ( LDT = 10, LWORK = 2*LDT*LDT ) * .. * .. Local Scalars .. INTEGER I, IFST, IFST1, IFST2, IFSTSV, ILST, ILST1, $ ILST2, ILSTSV, INFO1, INFO2, J, LOC, N REAL EPS, RES * .. * .. Local Arrays .. REAL Q( LDT, LDT ), RESULT( 2 ), T1( LDT, LDT ), $ T2( LDT, LDT ), TMP( LDT, LDT ), WORK( LWORK ) * .. * .. External Functions .. REAL SLAMCH EXTERNAL SLAMCH * .. * .. External Subroutines .. EXTERNAL SHST01, SLACPY, SLASET, STREXC * .. * .. Intrinsic Functions .. INTRINSIC ABS, SIGN * .. * .. Executable Statements .. * EPS = SLAMCH( 'P' ) RMAX = ZERO LMAX = 0 KNT = 0 NINFO( 1 ) = 0 NINFO( 2 ) = 0 NINFO( 3 ) = 0 * * Read input data until N=0 * 10 CONTINUE READ( NIN, FMT = * )N, IFST, ILST IF( N.EQ.0 ) $ RETURN KNT = KNT + 1 DO 20 I = 1, N READ( NIN, FMT = * )( TMP( I, J ), J = 1, N ) 20 CONTINUE CALL SLACPY( 'F', N, N, TMP, LDT, T1, LDT ) CALL SLACPY( 'F', N, N, TMP, LDT, T2, LDT ) IFSTSV = IFST ILSTSV = ILST IFST1 = IFST ILST1 = ILST IFST2 = IFST ILST2 = ILST RES = ZERO * * Test without accumulating Q * CALL SLASET( 'Full', N, N, ZERO, ONE, Q, LDT ) CALL STREXC( 'N', N, T1, LDT, Q, LDT, IFST1, ILST1, WORK, INFO1 ) DO 40 I = 1, N DO 30 J = 1, N IF( I.EQ.J .AND. Q( I, J ).NE.ONE ) $ RES = RES + ONE / EPS IF( I.NE.J .AND. Q( I, J ).NE.ZERO ) $ RES = RES + ONE / EPS 30 CONTINUE 40 CONTINUE * * Test with accumulating Q * CALL SLASET( 'Full', N, N, ZERO, ONE, Q, LDT ) CALL STREXC( 'V', N, T2, LDT, Q, LDT, IFST2, ILST2, WORK, INFO2 ) * * Compare T1 with T2 * DO 60 I = 1, N DO 50 J = 1, N IF( T1( I, J ).NE.T2( I, J ) ) $ RES = RES + ONE / EPS 50 CONTINUE 60 CONTINUE IF( IFST1.NE.IFST2 ) $ RES = RES + ONE / EPS IF( ILST1.NE.ILST2 ) $ RES = RES + ONE / EPS IF( INFO1.NE.INFO2 ) $ RES = RES + ONE / EPS * * Test for successful reordering of T2 * IF( INFO2.NE.0 ) THEN NINFO( INFO2 ) = NINFO( INFO2 ) + 1 ELSE IF( ABS( IFST2-IFSTSV ).GT.1 ) $ RES = RES + ONE / EPS IF( ABS( ILST2-ILSTSV ).GT.1 ) $ RES = RES + ONE / EPS END IF * * Test for small residual, and orthogonality of Q * CALL SHST01( N, 1, N, TMP, LDT, T2, LDT, Q, LDT, WORK, LWORK, $ RESULT ) RES = RES + RESULT( 1 ) + RESULT( 2 ) * * Test for T2 being in Schur form * LOC = 1 70 CONTINUE IF( T2( LOC+1, LOC ).NE.ZERO ) THEN * * 2 by 2 block * IF( T2( LOC, LOC+1 ).EQ.ZERO .OR. T2( LOC, LOC ).NE. $ T2( LOC+1, LOC+1 ) .OR. SIGN( ONE, T2( LOC, LOC+1 ) ).EQ. $ SIGN( ONE, T2( LOC+1, LOC ) ) )RES = RES + ONE / EPS DO 80 I = LOC + 2, N IF( T2( I, LOC ).NE.ZERO ) $ RES = RES + ONE / RES IF( T2( I, LOC+1 ).NE.ZERO ) $ RES = RES + ONE / RES 80 CONTINUE LOC = LOC + 2 ELSE * * 1 by 1 block * DO 90 I = LOC + 1, N IF( T2( I, LOC ).NE.ZERO ) $ RES = RES + ONE / RES 90 CONTINUE LOC = LOC + 1 END IF IF( LOC.LT.N ) $ GO TO 70 IF( RES.GT.RMAX ) THEN RMAX = RES LMAX = KNT END IF GO TO 10 * * End of SGET36 * END |