Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?lapll
Measures the linear dependence of two vectors.
Syntax
call slapll(n, x, incx, Y, incy, ssmin)
call dlapll(n, x, incx, Y, incy, ssmin)
call clapll(n, x, incx, Y, incy, ssmin)
call zlapll(n, x, incx, Y, incy, ssmin)
Include Files
mkl.fi
Description
Given two column vectors x and y of length n , let
A = (xy) be the n -by-2 matrix.
The routine ?lapll first computes the QR factorization of A as 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 .
Input Parameters
- n
-
INTEGER . The length of the vectors x and y .
- x
-
REAL for slapll DOUBLE PRECISION for dlapll COMPLEX for clapll DOUBLE COMPLEX for zlapll Array, DIMENSION (1+(n-1)incx) . On entry, x contains the n -vector x.
- y
-
REAL for slapll DOUBLE PRECISION for dlapll COMPLEX for clapll DOUBLE COMPLEX for zlapll Array, DIMENSION (1+( n -1) incy ). On entry, y contains the n -vector y.
- incx
-
INTEGER . The increment between successive elements of x; incx > 0 .
- incy
-
INTEGER . The increment between successive elements of y; incy > 0 .
Output Parameters
- x
-
On exit, x is overwritten.
- y
-
On exit, y is overwritten.
- ssmin
-
REAL for slapll / clapll DOUBLE PRECISION for dlapll / zlapll The smallest singular value of the n -by-2 matrix A = ( xy ).