Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
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?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).