Provided by: liblapack-doc_3.3.1-1_all #### NAME

```       LAPACK-3 - computes row and column scalings intended to equilibrate an M-by-N matrix A and
reduce its condition number

```

#### SYNOPSIS

```       SUBROUTINE CGEEQU( M, N, A, LDA, R, C, ROWCND, COLCND, AMAX, INFO )

INTEGER        INFO, LDA, M, N

REAL           AMAX, COLCND, ROWCND

REAL           C( * ), R( * )

COMPLEX        A( LDA, * )

```

#### PURPOSE

```       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.

```

#### ARGUMENTS

```        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.

A       (input) COMPLEX array, dimension (LDA,N)
The M-by-N matrix whose equilibration factors are
to be computed.

LDA     (input) INTEGER
The leading dimension of the array A.  LDA >= max(1,M).

R       (output) REAL array, dimension (M)
If INFO = 0 or INFO > M, R contains the row scale factors
for A.

C       (output) REAL array, dimension (N)
If INFO = 0,  C contains the column scale factors for A.

ROWCND  (output) 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  (output) 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    (output) 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    (output) 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

LAPACK routine (version 3.2)               April 2011                            CGEEQU(3lapack)
```