Purpose
  To perform the QR factorization
     (U ) = Q*(R),
     (x')     (0)
  where U and R are n-by-n upper triangular matrices, x is an
  n element vector and Q is an (n+1)-by-(n+1) orthogonal matrix.
  U must be supplied in the n-by-n upper triangular part of the
  array A and this is overwritten by R.
Specification
      SUBROUTINE MB04OX( N, A, LDA, X, INCX )
C     .. Scalar Arguments ..
      INTEGER            INCX, LDA, N
C     .. Array Arguments ..
      DOUBLE PRECISION   A(LDA,*), X(*)
Arguments
Input/Output Parameters
  N      (input) INTEGER
         The number of elements of X and the order of the square
         matrix A.  N >= 0.
  A      (input/output) DOUBLE PRECISION array, dimension (LDA,N)
         On entry, the leading N-by-N upper triangular part of this
         array must contain the upper triangular matrix U.
         On exit, the leading N-by-N upper triangular part of this
         array contains the upper triangular matrix R.
         The strict lower triangle of A is not referenced.
  LDA    INTEGER
         The leading dimension of the array A.  LDA >= max(1,N).
  X      (input/output) DOUBLE PRECISION array, dimension
         (1+(N-1)*INCX)
         On entry, the incremented array X must contain the
         vector x. On exit, the content of X is changed.
  INCX   (input) INTEGER.
         Specifies the increment for the elements of X.  INCX > 0.
Method
The matrix Q is formed as a sequence of plane rotations in planes (1, n+1), (2, n+1), ..., (n, n+1), the rotation in the (j, n+1)th plane, Q(j), being chosen to annihilate the jth element of x.Further Comments
NoneExample
Program Text
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