dlas2 man page on IRIX

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DLAS2(3F)							     DLAS2(3F)

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.

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