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dorbdb5.f(3) LAPACK dorbdb5.f(3)

NAME

dorbdb5.f

SYNOPSIS

Functions/Subroutines


subroutine dorbdb5 (M1, M2, N, X1, INCX1, X2, INCX2, Q1, LDQ1, Q2, LDQ2, WORK, LWORK, INFO)
DORBDB5

Function/Subroutine Documentation

subroutine dorbdb5 (integer M1, integer M2, integer N, double precision, dimension(*) X1, integer INCX1, double precision, dimension(*) X2, integer INCX2, double precision, dimension(ldq1,*) Q1, integer LDQ1, double precision, dimension(ldq2,*) Q2, integer LDQ2, double precision, dimension(*) WORK, integer LWORK, integer INFO)

DORBDB5

Purpose: 



 DORBDB5 orthogonalizes the column vector


      X = [ X1 ]


          [ X2 ]


 with respect to the columns of


      Q = [ Q1 ] .


          [ Q2 ]


 The columns of Q must be orthonormal.


 If the projection is zero according to Kahan's "twice is enough"


 criterion, then some other vector from the orthogonal complement


 is returned. This vector is chosen in an arbitrary but deterministic


 way.

Parameters:

M1 



          M1 is INTEGER


           The dimension of X1 and the number of rows in Q1. 0 <= M1.

M2



          M2 is INTEGER


           The dimension of X2 and the number of rows in Q2. 0 <= M2.

N



          N is INTEGER


           The number of columns in Q1 and Q2. 0 <= N.

X1



          X1 is DOUBLE PRECISION array, dimension (M1)


           On entry, the top part of the vector to be orthogonalized.


           On exit, the top part of the projected vector.

INCX1



          INCX1 is INTEGER


           Increment for entries of X1.

X2



          X2 is DOUBLE PRECISION array, dimension (M2)


           On entry, the bottom part of the vector to be


           orthogonalized. On exit, the bottom part of the projected


           vector.

INCX2



          INCX2 is INTEGER


           Increment for entries of X2.

Q1



          Q1 is DOUBLE PRECISION array, dimension (LDQ1, N)


           The top part of the orthonormal basis matrix.

LDQ1



          LDQ1 is INTEGER


           The leading dimension of Q1. LDQ1 >= M1.

Q2



          Q2 is DOUBLE PRECISION array, dimension (LDQ2, N)


           The bottom part of the orthonormal basis matrix.

LDQ2



          LDQ2 is INTEGER


           The leading dimension of Q2. LDQ2 >= M2.

WORK



          WORK is DOUBLE PRECISION array, dimension (LWORK)

LWORK



          LWORK is INTEGER


           The dimension of the array WORK. LWORK >= N.

INFO



          INFO is INTEGER


           = 0:  successful exit.


           < 0:  if INFO = -i, the i-th argument had an illegal value.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

July 2012

Definition at line 158 of file dorbdb5.f.

Author

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