SRC/slasv2.f(3)            Library Functions Manual            SRC/slasv2.f(3)

NAME
       SRC/slasv2.f

SYNOPSIS
   Functions/Subroutines
       subroutine slasv2 (f, g, h, ssmin, ssmax, snr, csr, snl, csl)
           SLASV2 computes the singular value decomposition of a 2-by-2
           triangular matrix.

Function/Subroutine Documentation
   subroutine slasv2 (real f, real g, real h, real ssmin, real ssmax, real
       snr, real csr, real snl, real csl)
       SLASV2 computes the singular value decomposition of a 2-by-2 triangular
       matrix.

       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 ].
           !>

       Parameters
           F

           !>          F is REAL
           !>          The (1,1) element of the 2-by-2 matrix.
           !>

           G

           !>          G is REAL
           !>          The (1,2) element of the 2-by-2 matrix.
           !>

           H

           !>          H is REAL
           !>          The (2,2) element of the 2-by-2 matrix.
           !>

           SSMIN

           !>          SSMIN is REAL
           !>          abs(SSMIN) is the smaller singular value.
           !>

           SSMAX

           !>          SSMAX is REAL
           !>          abs(SSMAX) is the larger singular value.
           !>

           SNL

           !>          SNL is REAL
           !>

           CSL

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

           SNR

           !>          SNR is REAL
           !>

           CSR

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

       Author
           Univ. of Tennessee


           Univ. of California Berkeley


           Univ. of Colorado Denver


           NAG Ltd.

       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).
           !>
           !>  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.
           !>

       Definition at line 135 of file slasv2.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0                 SRC/slasv2.f(3)