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SLASV2(3F)							    SLASV2(3F)

NAME
     SLASV2 - compute the singular value decomposition of a 2-by-2 triangular
     matrix  [ F G ]  [ 0 H ]

SYNOPSIS
     SUBROUTINE SLASV2( F, G, H, SSMIN, SSMAX, SNR, CSR, SNL, CSL )

	 REAL		CSL, CSR, F, G, H, SNL, SNR, SSMAX, SSMIN

PURPOSE
     SLASV2 computes the singular value decomposition of a 2-by-2 triangular
     matrix
	[  F   G  ]
	[  0   H  ].  On return, abs(SSMAX) is the larger singular value,
     abs(SSMIN) is the smaller singular value, and (CSL,SNL) and (CSR,SNR) are
     the left and right singular vectors for abs(SSMAX), giving the
     decomposition

	[ CSL  SNL ] [	F   G  ] [ CSR -SNR ]  =  [ SSMAX   0	]
	[-SNL  CSL ] [	0   H  ] [ SNR	CSR ]	  [  0	  SSMIN ].

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

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

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

     SSMIN   (output) REAL
	     abs(SSMIN) is the smaller singular value.

     SSMAX   (output) REAL
	     abs(SSMAX) is the larger singular value.

     SNL     (output) REAL
	     CSL     (output) REAL The vector (CSL, SNL) is a unit left
	     singular vector for the singular value abs(SSMAX).

     SNR     (output) REAL
	     CSR     (output) REAL The vector (CSR, SNR) is a unit right
	     singular vector for the singular value abs(SSMAX).

FURTHER DETAILS
     Any input parameter may be aliased with any output parameter.

     Barring over/underflow and assuming a guard digit in subtraction, all
     output quantities are correct to within a few units in the last place
     (ulps).

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SLASV2(3F)							    SLASV2(3F)

     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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