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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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| subroutine cgeequ | ( | integer | M, |
| integer | N, | ||
| complex, dimension( lda, * ) | A, | ||
| integer | LDA, | ||
| real, dimension( * ) | R, | ||
| real, dimension( * ) | C, | ||
| real | ROWCND, | ||
| real | COLCND, | ||
| real | AMAX, | ||
| integer | INFO | ||
| ) |
CGEEQU
Download CGEEQU + dependencies [TGZ] [ZIP] [TXT]
CGEEQU 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.
| [in] | M | M is INTEGER
The number of rows of the matrix A. M >= 0. |
| [in] | N | N is INTEGER
The number of columns of the matrix A. N >= 0. |
| [in] | A | A is COMPLEX array, dimension (LDA,N)
The M-by-N matrix whose equilibration factors are
to be computed. |
| [in] | LDA | LDA is INTEGER
The leading dimension of the array A. LDA >= max(1,M). |
| [out] | R | R is REAL array, dimension (M)
If INFO = 0 or INFO > M, R contains the row scale factors
for A. |
| [out] | C | C is REAL array, dimension (N)
If INFO = 0, C contains the column scale factors for A. |
| [out] | ROWCND | 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. |
| [out] | COLCND | 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. |
| [out] | AMAX | 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. |
| [out] | INFO | 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 |
1.9.4