Move LAPACK trunk into position.

1 files changed, 97 insertions, 0 deletions

diff --git a/SRC/dlaqr1.f b/SRC/dlaqr1.f
new file mode 100644
index 00000000..c80fe668
--- /dev/null
+++ b/SRC/dlaqr1.f
@@ -0,0 +1,97 @@
+      SUBROUTINE DLAQR1( N, H, LDH, SR1, SI1, SR2, SI2, V )
+*
+*  -- LAPACK auxiliary routine (version 3.1) --
+*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
+*     November 2006
+*
+*     .. Scalar Arguments ..
+      DOUBLE PRECISION   SI1, SI2, SR1, SR2
+      INTEGER            LDH, N
+*     ..
+*     .. Array Arguments ..
+      DOUBLE PRECISION   H( LDH, * ), V( * )
+*     ..
+*
+*       Given a 2-by-2 or 3-by-3 matrix H, DLAQR1 sets v to a
+*       scalar multiple of the first column of the product
+*
+*       (*)  K = (H - (sr1 + i*si1)*I)*(H - (sr2 + i*si2)*I)
+*
+*       scaling to avoid overflows and most underflows. It
+*       is assumed that either
+*
+*               1) sr1 = sr2 and si1 = -si2
+*           or
+*               2) si1 = si2 = 0.
+*
+*       This is useful for starting double implicit shift bulges
+*       in the QR algorithm.
+*
+*
+*       N      (input) integer
+*              Order of the matrix H. N must be either 2 or 3.
+*
+*       H      (input) DOUBLE PRECISION array of dimension (LDH,N)
+*              The 2-by-2 or 3-by-3 matrix H in (*).
+*
+*       LDH    (input) integer
+*              The leading dimension of H as declared in
+*              the calling procedure.  LDH.GE.N
+*
+*       SR1    (input) DOUBLE PRECISION
+*       SI1    The shifts in (*).
+*       SR2
+*       SI2
+*
+*       V      (output) DOUBLE PRECISION array of dimension N
+*              A scalar multiple of the first column of the
+*              matrix K in (*).
+*
+*     ================================================================
+*     Based on contributions by
+*        Karen Braman and Ralph Byers, Department of Mathematics,
+*        University of Kansas, USA
+*
+*     ================================================================
+*
+*     .. Parameters ..
+      DOUBLE PRECISION   ZERO
+      PARAMETER          ( ZERO = 0.0d0 )
+*     ..
+*     .. Local Scalars ..
+      DOUBLE PRECISION   H21S, H31S, S
+*     ..
+*     .. Intrinsic Functions ..
+      INTRINSIC          ABS
+*     ..
+*     .. Executable Statements ..
+      IF( N.EQ.2 ) THEN
+         S = ABS( H( 1, 1 )-SR2 ) + ABS( SI2 ) + ABS( H( 2, 1 ) )
+         IF( S.EQ.ZERO ) THEN
+            V( 1 ) = ZERO
+            V( 2 ) = ZERO
+         ELSE
+            H21S = H( 2, 1 ) / S
+            V( 1 ) = H21S*H( 1, 2 ) + ( H( 1, 1 )-SR1 )*
+     $               ( ( H( 1, 1 )-SR2 ) / S ) - SI1*( SI2 / S )
+            V( 2 ) = H21S*( H( 1, 1 )+H( 2, 2 )-SR1-SR2 )
+         END IF
+      ELSE
+         S = ABS( H( 1, 1 )-SR2 ) + ABS( SI2 ) + ABS( H( 2, 1 ) ) +
+     $       ABS( H( 3, 1 ) )
+         IF( S.EQ.ZERO ) THEN
+            V( 1 ) = ZERO
+            V( 2 ) = ZERO
+            V( 3 ) = ZERO
+         ELSE
+            H21S = H( 2, 1 ) / S
+            H31S = H( 3, 1 ) / S
+            V( 1 ) = ( H( 1, 1 )-SR1 )*( ( H( 1, 1 )-SR2 ) / S ) -
+     $               SI1*( SI2 / S ) + H( 1, 2 )*H21S + H( 1, 3 )*H31S
+            V( 2 ) = H21S*( H( 1, 1 )+H( 2, 2 )-SR1-SR2 ) +
+     $               H( 2, 3 )*H31S
+            V( 3 ) = H31S*( H( 1, 1 )+H( 3, 3 )-SR1-SR2 ) +
+     $               H21S*H( 3, 2 )
+         END IF
+      END IF
+      END