sget40()

subroutine sget40	(	real	rmax,
		integer	lmax,
		integer, dimension( 2 )	ninfo,
		integer	knt,
		integer	nin
	)

SGET40

Purpose:

 SGET40 tests STGEXC, a routine for swapping adjacent blocks (either
 1 by 1 or 2 by 2) on the diagonal of a pencil in real generalized Schur form.
 Thus, STGEXC computes an orthogonal matrices Q and Z such that

     Q' * ( [ A B ], [ D E ] ) * Z  = ( [ C1 B1 ], [ F1 E1 ] )
          ( [ 0 C ]  [   F ] )        ( [ 0  A1 ]  [    D1]  )

 where (C1,F1) is similar to (C,F) and (A1,D1) is similar to (A,D).
 Both (A,D) and (C,F) are assumed to be in standard form
 and (A1,D1) and (C1,F1) are returned with the
 same properties.

Parameters

[out]	RMAX	RMAX is REAL Value of the largest test ratio.
[out]	LMAX	LMAX is INTEGER Example number where largest test ratio achieved.
[out]	NINFO	NINFO is INTEGER array, dimension (2) NINFO( 1 ) = STGEXC without accumulation returned INFO nonzero NINFO( 2 ) = STGEXC with accumulation returned INFO nonzero
[out]	KNT	KNT is INTEGER Total number of examples tested.
[in]	NIN	NIN is INTEGER Input logical unit number.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 84 of file sget40.f.

*
*  -- LAPACK test routine --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
*     .. Scalar Arguments ..
      INTEGER            KNT, LMAX, NIN
      REAL               RMAX
*     ..
*     .. Array Arguments ..
      INTEGER            NINFO( 2 )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      REAL               ZERO, ONE
      parameter( zero = 0.0, one = 1.0 )
      INTEGER            LDT, LWORK
      parameter( ldt = 10, lwork = 100 + 4*ldt + 16 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, IFST, IFST1, IFST2, IFSTSV, ILST, ILST1,
     $                   ILST2, ILSTSV, J, LOC, N
      REAL               EPS, RES
*     ..
*     .. Local Arrays ..
      REAL               Q( LDT, LDT ), Z( LDT, LDT ), RESULT( 4 ),
     $                   T( LDT, LDT ), T1( LDT, LDT ), T2( LDT, LDT ),
     $                   S( LDT, LDT ), S1( LDT, LDT ), S2( LDT, LDT ),
     $                   TMP( LDT, LDT ), WORK( LWORK )
*     ..
*     .. External Functions ..
      REAL               SLAMCH
      EXTERNAL           slamch
*     ..
*     .. External Subroutines ..
      EXTERNAL           sget51, slacpy, slaset, stgexc
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          abs, sign
*     ..
*     .. Executable Statements ..
*
      eps = slamch( 'P' )
      rmax = zero
      lmax = 0
      knt = 0
      ninfo( 1 ) = 0
      ninfo( 2 ) = 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, t, ldt )
      CALL slacpy( 'F', n, n, tmp, ldt, t1, ldt )
      CALL slacpy( 'F', n, n, tmp, ldt, t2, ldt )
      DO 25 i = 1, n
         READ( nin, fmt = * )( tmp( i, j ), j = 1, n )
   25 CONTINUE
      CALL slacpy( 'F', n, n, tmp, ldt, s, ldt )
      CALL slacpy( 'F', n, n, tmp, ldt, s1, ldt )
      CALL slacpy( 'F', n, n, tmp, ldt, s2, ldt )
      ifstsv = ifst
      ilstsv = ilst
      ifst1 = ifst
      ilst1 = ilst
      ifst2 = ifst
      ilst2 = ilst
      res = zero
*
*     Test without accumulating Q and Z
*
      CALL slaset( 'Full', n, n, zero, one, q, ldt )
      CALL slaset( 'Full', n, n, zero, one, z, ldt )
      CALL stgexc( .false., .false., n, t1, ldt, s1, ldt, q, ldt,
     $             z, ldt, ifst1, ilst1, work, lwork, ninfo( 1 ) )
      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
            IF( i.EQ.j .AND. z( i, j ).NE.one )
     $         res = res + one / eps
            IF( i.NE.j .AND. z( 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 slaset( 'Full', n, n, zero, one, z, ldt )
      CALL stgexc( .true., .true., n, t2, ldt, s2, ldt, q, ldt,
     $             z, ldt, ifst2, ilst2, work, lwork, ninfo( 2 ) )
*
*     Compare T1 with T2 and S1 with S2
*
      DO 60 i = 1, n
         DO 50 j = 1, n
            IF( t1( i, j ).NE.t2( i, j ) )
     $         res = res + one / eps
            IF( s1( i, j ).NE.s2( 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( ninfo( 1 ).NE.ninfo( 2 ) )
     $   res = res + one / eps
*
*     Test orthogonality of Q and Z and backward error on T2 and S2
*
      CALL sget51( 1, n, t, ldt, t2, ldt, q, ldt, z, ldt, work,
     $             result( 1 ) )
      CALL sget51( 1, n, s, ldt, s2, ldt, q, ldt, z, ldt, work,
     $             result( 2 ) )
      CALL sget51( 3, n, t, ldt, t2, ldt, q, ldt, q, ldt, work,
     $             result( 3 ) )
      CALL sget51( 3, n, t, ldt, t2, ldt, z, ldt, z, ldt, work,
     $             result( 4 ) )
      res = res + result( 1 ) + result( 2 ) + result( 3 ) + result( 4 )
*
*     Read next matrix pair
*
      GO TO 10
*
*     End of SGET40
*

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