sgeequ.f(3) LAPACK sgeequ.f(3)
subroutine sgeequ (M, N, A, LDA, R, C, ROWCND, COLCND, AMAX, INFO)
subroutine sgeequ (integerM, integerN, real, dimension( lda, * )A, integerLDA, real,
dimension( * )R, real, dimension( * )C, realROWCND, realCOLCND, realAMAX, integerINFO)
SGEEQU computes row and column scalings intended to equilibrate an
M-by-N matrix A and reduce its condition number. R returns the row
scale factors and C the column scale factors, chosen to try to make
the largest element in each row and column of the matrix B with
elements B(i,j)=R(i)*A(i,j)*C(j) have absolute value 1.
R(i) and C(j) are restricted to be between SMLNUM = smallest safe
number and BIGNUM = largest safe number. Use of these scaling
factors is not guaranteed to reduce the condition number of A but
works well in practice.
M is INTEGER
The number of rows of the matrix A. M >= 0.
N is INTEGER
The number of columns of the matrix A. N >= 0.
A is REAL array, dimension (LDA,N)
The M-by-N matrix whose equilibration factors are
to be computed.
LDA is INTEGER
The leading dimension of the array A. LDA >= max(1,M).
R is REAL array, dimension (M)
If INFO = 0 or INFO > M, R contains the row scale factors
C is REAL array, dimension (N)
If INFO = 0, C contains the column scale factors for A.
ROWCND is REAL
If INFO = 0 or INFO > M, ROWCND contains the ratio of the
smallest R(i) to the largest R(i). If ROWCND >= 0.1 and
AMAX is neither too large nor too small, it is not worth
scaling by R.
COLCND is REAL
If INFO = 0, COLCND contains the ratio of the smallest
C(i) to the largest C(i). If COLCND >= 0.1, it is not
worth scaling by C.
AMAX is REAL
Absolute value of largest matrix element. If AMAX is very
close to overflow or very close to underflow, the matrix
should be scaled.
INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, and i is
<= M: the i-th row of A is exactly zero
> M: the (i-M)-th column of A is exactly zero
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
Definition at line 139 of file sgeequ.f.
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 sgeequ.f(3)