
dlas2.f(3) LAPACK dlas2.f(3)
NAME
dlas2.f 
SYNOPSIS
Functions/Subroutines
subroutine dlas2 (F, G, H, SSMIN, SSMAX)
DLAS2 computes singular values of a 2by2 triangular matrix.
Function/Subroutine Documentation
subroutine dlas2 (double precisionF, double precisionG, double precisionH, double
precisionSSMIN, double precisionSSMAX)
DLAS2 computes singular values of a 2by2 triangular matrix.
Purpose:
DLAS2 computes the singular values of the 2by2 matrix
[ F G ]
[ 0 H ].
On return, SSMIN is the smaller singular value and SSMAX is the
larger singular value.
Parameters:
F
F is DOUBLE PRECISION
The (1,1) element of the 2by2 matrix.
G
G is DOUBLE PRECISION
The (1,2) element of the 2by2 matrix.
H
H is DOUBLE PRECISION
The (2,2) element of the 2by2 matrix.
SSMIN
SSMIN is DOUBLE PRECISION
The smaller singular value.
SSMAX
SSMAX is DOUBLE PRECISION
The larger singular value.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Further Details:
Barring over/underflow, all output quantities are correct to within
a few units in the last place (ulps), even in the absence of a guard
digit in addition/subtraction.
In IEEE arithmetic, the code works correctly if one matrix element is
infinite.
Overflow will not occur unless the largest singular value itself
overflows, or is within a few ulps of overflow. (On machines with
partial overflow, like the Cray, overflow may occur if the largest
singular value is within a factor of 2 of overflow.)
Underflow is harmless if underflow is gradual. Otherwise, results
may correspond to a matrix modified by perturbations of size near
the underflow threshold.
Definition at line 108 of file dlas2.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 dlas2.f(3) 
