DLASQ2(3F) DLASQ2(3F)
DLASQ2 - DLASQ2 computes the singular values of a real N-by-N unreduced
bidiagonal matrix with squared diagonal elements in Q and squared offdiagonal
elements in E
SUBROUTINE DLASQ2( M, Q, E, QQ, EE, EPS, TOL2, SMALL2, SUP, KEND, INFO )
INTEGER INFO, KEND, M
DOUBLE PRECISION EPS, SMALL2, SUP, TOL2
DOUBLE PRECISION E( * ), EE( * ), Q( * ), QQ( * )
DLASQ2 computes the singular values of a real N-by-N unreduced
bidiagonal matrix with squared diagonal elements in Q and
squared off-diagonal elements in E. The singular values are
computed to relative accuracy TOL, barring over/underflow or
denormalization.
M (input) INTEGER
The number of rows and columns in the matrix. M >= 0.
Q (output) DOUBLE PRECISION array, dimension (M)
On normal exit, contains the squared singular values.
E (workspace) DOUBLE PRECISION array, dimension (M)
QQ (input/output) DOUBLE PRECISION array, dimension (M)
On entry, QQ contains the squared diagonal elements of the
bidiagonal matrix whose SVD is desired. On exit, QQ is
overwritten.
EE (input/output) DOUBLE PRECISION array, dimension (M)
On entry, EE(1:N-1) contains the squared off-diagonal elements of
the bidiagonal matrix whose SVD is desired. On exit, EE is
overwritten.
EPS (input) DOUBLE PRECISION
Machine epsilon.
TOL2 (input) DOUBLE PRECISION
Desired relative accuracy of computed eigenvalues as defined in
DLASQ1.
SMALL2 (input) DOUBLE PRECISION
A threshold value as defined in DLASQ1.
Page 1
DLASQ2(3F) DLASQ2(3F)
SUP (input/output) DOUBLE PRECISION
Upper bound for the smallest eigenvalue.
KEND (input/output) INTEGER
Index where minimum d occurs.
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, the algorithm did not converge; i specifies
how many superdiagonals did not converge.
DLASQ2(3F) DLASQ2(3F)
DLASQ2 - DLASQ2 computes the singular values of a real N-by-N unreduced
bidiagonal matrix with squared diagonal elements in Q and squared offdiagonal
elements in E
SUBROUTINE DLASQ2( M, Q, E, QQ, EE, EPS, TOL2, SMALL2, SUP, KEND, INFO )
INTEGER INFO, KEND, M
DOUBLE PRECISION EPS, SMALL2, SUP, TOL2
DOUBLE PRECISION E( * ), EE( * ), Q( * ), QQ( * )
DLASQ2 computes the singular values of a real N-by-N unreduced
bidiagonal matrix with squared diagonal elements in Q and
squared off-diagonal elements in E. The singular values are
computed to relative accuracy TOL, barring over/underflow or
denormalization.
M (input) INTEGER
The number of rows and columns in the matrix. M >= 0.
Q (output) DOUBLE PRECISION array, dimension (M)
On normal exit, contains the squared singular values.
E (workspace) DOUBLE PRECISION array, dimension (M)
QQ (input/output) DOUBLE PRECISION array, dimension (M)
On entry, QQ contains the squared diagonal elements of the
bidiagonal matrix whose SVD is desired. On exit, QQ is
overwritten.
EE (input/output) DOUBLE PRECISION array, dimension (M)
On entry, EE(1:N-1) contains the squared off-diagonal elements of
the bidiagonal matrix whose SVD is desired. On exit, EE is
overwritten.
EPS (input) DOUBLE PRECISION
Machine epsilon.
TOL2 (input) DOUBLE PRECISION
Desired relative accuracy of computed eigenvalues as defined in
DLASQ1.
SMALL2 (input) DOUBLE PRECISION
A threshold value as defined in DLASQ1.
Page 1
DLASQ2(3F) DLASQ2(3F)
SUP (input/output) DOUBLE PRECISION
Upper bound for the smallest eigenvalue.
KEND (input/output) INTEGER
Index where minimum d occurs.
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, the algorithm did not converge; i specifies
how many superdiagonals did not converge.
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