GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 4.8 |
i386 |
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dlaqgb(l) |
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DLAQGB - equilibrate a general M by N band matrix A with KL subdiagonals and KU superdiagonals using the row and scaling factors in the vectors R and C
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SUBROUTINE DLAQGB( |
M, N, KL, KU, AB, LDAB, R, C, ROWCND, COLCND, AMAX, EQUED ) | ||
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CHARACTER |
EQUED | ||
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INTEGER |
KL, KU, LDAB, M, N | ||
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DOUBLE |
PRECISION AMAX, COLCND, ROWCND | ||
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DOUBLE |
PRECISION AB( LDAB, * ), C( * ), R( * ) |
DLAQGB equilibrates a general M by N band matrix A with KL subdiagonals and KU superdiagonals using the row and scaling factors in the vectors R and C.
M (input) INTEGER
The number of rows of the matrix A. M >= 0.
N (input) INTEGER
The number of columns of the matrix A. N >= 0.
KL (input) INTEGER
The number of subdiagonals within the band of A. KL >= 0.
KU (input) INTEGER
The number of superdiagonals within the band of A. KU >= 0.
AB (input/output) DOUBLE PRECISION array, dimension (LDAB,N)
On entry, the matrix A in band storage, in rows 1 to KL+KU+1. The j-th column of A is stored in the j-th column of the array AB as follows: AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl)
On exit, the equilibrated matrix, in the same storage format as A. See EQUED for the form of the equilibrated matrix.
LDAB (input) INTEGER
The leading dimension of the array AB. LDA >= KL+KU+1.
R (output) DOUBLE PRECISION array, dimension (M)
The row scale factors for A.
C (output) DOUBLE PRECISION array, dimension (N)
The column scale factors for A.
ROWCND (output) DOUBLE PRECISION
Ratio of the smallest R(i) to the largest R(i).
COLCND (output) DOUBLE PRECISION
Ratio of the smallest C(i) to the largest C(i).
AMAX (input) DOUBLE PRECISION
Absolute value of largest matrix entry.
EQUED (output) CHARACTER*1
Specifies the form of
equilibration that was done. = ’N’: No
equilibration
= ’R’: Row equilibration, i.e., A has been
premultiplied by diag(R). = ’C’: Column
equilibration, i.e., A has been postmultiplied by diag(C). =
’B’: Both row and column equilibration, i.e., A
has been replaced by diag(R) * A * diag(C).
THRESH is a threshold value used to decide if row or column scaling should be done based on the ratio of the row or column scaling factors. If ROWCND < THRESH, row scaling is done, and if COLCND < THRESH, column scaling is done.
LARGE and SMALL are threshold values used to decide if row scaling should be done based on the absolute size of the largest matrix element. If AMAX > LARGE or AMAX < SMALL, row scaling is done.
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dlaqgb(l) | |