redhat man page for dlas2

DLAS2(l)								 )								  DLAS2(l)

NAME
       DLAS2 - compute the singular values of the 2-by-2 matrix [ F G ] [ 0 H ]

SYNOPSIS
       SUBROUTINE DLAS2( F, G, H, SSMIN, SSMAX )

	   DOUBLE	 PRECISION F, G, H, SSMAX, SSMIN

PURPOSE
       DLAS2  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.

ARGUMENTS
       F       (input) DOUBLE PRECISION
	       The (1,1) element of the 2-by-2 matrix.

       G       (input) DOUBLE PRECISION
	       The (1,2) element of the 2-by-2 matrix.

       H       (input) DOUBLE PRECISION
	       The (2,2) element of the 2-by-2 matrix.

       SSMIN   (output) DOUBLE PRECISION
	       The smaller singular value.

       SSMAX   (output) DOUBLE PRECISION
	       The larger singular value.

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.

LAPACK version 3.0						   15 June 2000 							  DLAS2(l)