slas2()

subroutine slas2	(	real	f,
		real	g,
		real	h,
		real	ssmin,
		real	ssmax )

SLAS2 computes singular values of a 2-by-2 triangular matrix.

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Purpose:

!>
!> SLAS2  computes the singular values of the 2-by-2 matrix
!>    [  F   G  ]
!>    [  0   H  ].
!> On return, SSMIN is the smaller singular value and SSMAX is the
!> larger singular value.
!> 

Parameters

[in]	F	!> F is REAL !> The (1,1) element of the 2-by-2 matrix. !>
[in]	G	!> G is REAL !> The (1,2) element of the 2-by-2 matrix. !>
[in]	H	!> H is REAL !> The (2,2) element of the 2-by-2 matrix. !>
[out]	SSMIN	!> SSMIN is REAL !> The smaller singular value. !>
[out]	SSMAX	!> SSMAX is REAL !> The larger singular value. !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

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.
!>
!>  Underflow is harmless if underflow is gradual. Otherwise, results
!>  may correspond to a matrix modified by perturbations of size near
!>  the underflow threshold.
!>