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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



     #include <sunperf.h>

     void dlas2(double f, double g, double h, double *ssmin, dou-
               ble *ssmax) ;

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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