man slapll (Fonctions bibliothèques) - 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 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.
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 ).