# zunbdb6 (3) - Linux Manuals

zunbdb6.f -

## SYNOPSIS

### Functions/Subroutines

subroutine zunbdb6 (M1, M2, N, X1, INCX1, X2, INCX2, Q1, LDQ1, Q2, LDQ2, WORK, LWORK, INFO)
ZUNBDB6

## Function/Subroutine Documentation

### subroutine zunbdb6 (integerM1, integerM2, integerN, complex*16, dimension(*)X1, integerINCX1, complex*16, dimension(*)X2, integerINCX2, complex*16, dimension(ldq1,*)Q1, integerLDQ1, complex*16, dimension(ldq2,*)Q2, integerLDQ2, complex*16, dimension(*)WORK, integerLWORK, integerINFO)

ZUNBDB6 .SH "Purpose:"

``` ZUNBDB6 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 the zero vector is returned..fi

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 COMPLEX*16 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 COMPLEX*16 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 COMPLEX*16 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 COMPLEX*16 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 COMPLEX*16 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