# zlapll.f man page

zlapll.f —

## Synopsis

### Functions/Subroutines

subroutinezlapll(N, X, INCX, Y, INCY, SSMIN)ZLAPLLmeasures the linear dependence of two vectors.

## Function/Subroutine Documentation

### subroutine zlapll (integerN, complex*16, dimension( * )X, integerINCX, complex*16, dimension( * )Y, integerINCY, double precisionSSMIN)

**ZLAPLL** measures the linear dependence of two vectors.

**Purpose:**

```
Given two column vectors X and Y, let
A = ( X Y ).
The subroutine first computes the QR factorization of A = Q*R,
and then computes the SVD of the 2-by-2 upper triangular matrix R.
The smaller singular value of R is returned in SSMIN, which is used
as the measurement of the linear dependency of the vectors X and Y.
```

**Parameters:**

*N*

```
N is INTEGER
The length of the vectors X and Y.
```

*X*

```
X is COMPLEX*16 array, dimension (1+(N-1)*INCX)
On entry, X contains the N-vector X.
On exit, X is overwritten.
```

*INCX*

```
INCX is INTEGER
The increment between successive elements of X. INCX > 0.
```

*Y*

```
Y is COMPLEX*16 array, dimension (1+(N-1)*INCY)
On entry, Y contains the N-vector Y.
On exit, Y is overwritten.
```

*INCY*

```
INCY is INTEGER
The increment between successive elements of Y. INCY > 0.
```

*SSMIN*

```
SSMIN is DOUBLE PRECISION
The smallest singular value of the N-by-2 matrix A = ( X Y ).
```

**Author:**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**

September 2012

Definition at line 101 of file zlapll.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

zlapll(3) is an alias of zlapll.f(3).