---
name: "slapll"
section: "3lapack"
platform: "linux"
package: "liblapack-doc"
version: "3.2.1-8"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/slapll/3lapack"
---

# slapll(3lapack)

two column vectors X and Y, let A = ( X Y )

## NAME

SLAPLL - two column vectors X and Y, let   A = ( X Y )

## SYNOPSIS

- SUBROUTINE SLAPLL(

  N, X, INCX, Y, INCY, SSMIN )

- INTEGER

  INCX, INCY, N

- REAL

  SSMIN

- REAL

  X( \* ), Y( \* )

## PURPOSE

Given two column vectors X and Y, let 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.

## ARGUMENTS

- N (input) INTEGER

  The length of the vectors X and Y.

- X (input/output) REAL array,

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

- INCX (input) INTEGER

  The increment between successive elements of X. INCX \> 0.

- Y (input/output) REAL array,

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

- INCY (input) INTEGER

  The increment between successive elements of Y. INCY \> 0.

- SSMIN (output) REAL

  The smallest singular value of the N-by-2 matrix A = ( X Y ).