dlas2 (l)  Linux Man Pages
dlas2: computes the singular values of the 2by2 matrix [ F G ] [ 0 H ]
Command to display dlas2
manual in Linux: $ man l dlas2
NAME
DLAS2  computes the singular values of the 2by2 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 2by2 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 2by2 matrix.
 G (input) DOUBLE PRECISION

The (1,2) element of the 2by2 matrix.
 H (input) DOUBLE PRECISION

The (2,2) element of the 2by2 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.
Pages related to dlas2
 dlas2 (3)
 dlascl (l)  multiplies the M by N real matrix A by the real scalar CTO/CFROM
 dlascl2 (l)  performs a diagonal scaling on a vector
 dlasd0 (l)  a divide and conquer approach, DLASD0 computes the singular value decomposition (SVD) of a real upper bidiagonal NbyM matrix B with diagonal D and offdiagonal E, where M = N + SQRE
 dlasd1 (l)  computes the SVD of an upper bidiagonal NbyM matrix B,
 dlasd2 (l)  merges the two sets of singular values together into a single sorted set
 dlasd3 (l)  finds all the square roots of the roots of the secular equation, as defined by the values in D and Z
 dlasd4 (l)  subroutine compute the square root of the Ith updated eigenvalue of a positive symmetric rankone modification to a positive diagonal matrix whose entries are given as the squares of the corresponding entries in the array d, and that 0 <= D(i) < D(j) for i < j and that RHO > 0
 dlasd5 (l)  subroutine compute the square root of the Ith eigenvalue of a positive symmetric rankone modification of a 2by2 diagonal matrix diag( D ) * diag( D ) + RHO The diagonal entries in the array D are assumed to satisfy 0 <= D(i) < D(j) for i < j
 dlasd6 (l)  computes the SVD of an updated upper bidiagonal matrix B obtained by merging two smaller ones by appending a row
 dlasd7 (l)  merges the two sets of singular values together into a single sorted set