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dlaqr1(3) [centos man page]

dlaqr1.f(3)							      LAPACK							       dlaqr1.f(3)

NAME

       dlaqr1.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dlaqr1 (N, H, LDH, SR1, SI1, SR2, SI2, V)
	   DLAQR1 sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3 matrix H and specified shifts.

Function/Subroutine Documentation
   subroutine dlaqr1 (integerN, double precision, dimension( ldh, * )H, integerLDH, double precisionSR1, double precisionSI1, double precisionSR2,
       double precisionSI2, double precision, dimension( * )V)
       DLAQR1 sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3 matrix H and specified shifts.

       Purpose:

		 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.

       Parameters:
	   N

		     N is integer
			 Order of the matrix H. N must be either 2 or 3.

	   H

		     H is DOUBLE PRECISION array of dimension (LDH,N)
			 The 2-by-2 or 3-by-3 matrix H in (*).

	   LDH

		     LDH is integer
			 The leading dimension of H as declared in
			 the calling procedure.  LDH.GE.N

	   SR1

		     SR1 is DOUBLE PRECISION

	   SI1

		     SI1 is DOUBLE PRECISION

	   SR2

		     SR2 is DOUBLE PRECISION

	   SI2

		     SI2 is DOUBLE PRECISION
			 The shifts in (*).

	   V

		     V is DOUBLE PRECISION array of dimension N
			 A scalar multiple of the first column of the
			 matrix K in (*).

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   September 2012

       Contributors:
	   Karen Braman and Ralph Byers, Department of Mathematics, University of Kansas, USA

       Definition at line 122 of file dlaqr1.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2							  Tue Sep 25 2012						       dlaqr1.f(3)

Check Out this Related Man Page

claqr1.f(3)							      LAPACK							       claqr1.f(3)

NAME

       claqr1.f -

SYNOPSIS

   Functions/Subroutines
       subroutine claqr1 (N, H, LDH, S1, S2, V)
	   CLAQR1 sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3 matrix H and specified shifts.

Function/Subroutine Documentation
   subroutine claqr1 (integerN, complex, dimension( ldh, * )H, integerLDH, complexS1, complexS2, complex, dimension( * )V)
       CLAQR1 sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3 matrix H and specified shifts.

       Purpose:

		 Given a 2-by-2 or 3-by-3 matrix H, CLAQR1 sets v to a
		 scalar multiple of the first column of the product

		 (*)  K = (H - s1*I)*(H - s2*I)

		 scaling to avoid overflows and most underflows.

		 This is useful for starting double implicit shift bulges
		 in the QR algorithm.

       Parameters:
	   N

		     N is integer
			 Order of the matrix H. N must be either 2 or 3.

	   H

		     H is COMPLEX array of dimension (LDH,N)
			 The 2-by-2 or 3-by-3 matrix H in (*).

	   LDH

		     LDH is integer
			 The leading dimension of H as declared in
			 the calling procedure.  LDH.GE.N

	   S1

		     S1 is COMPLEX

	   S2

		     S2 is COMPLEX

		     S1 and S2 are the shifts defining K in (*) above.

	   V

		     V is COMPLEX array of dimension N
			 A scalar multiple of the first column of the
			 matrix K in (*).

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   September 2012

       Contributors:
	   Karen Braman and Ralph Byers, Department of Mathematics, University of Kansas, USA

       Definition at line 108 of file claqr1.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2							  Tue Sep 25 2012						       claqr1.f(3)
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