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cgeequ (3)
  • >> cgeequ (3) ( Solaris man: Библиотечные вызовы )
  • 
    NAME
         cgeequ - compute row and column scalings intended to equili-
         brate 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, * )
    
    
    
         #include <sunperf.h>
    
         void cgeequ(int m, int n, complex *ca, int  lda,  float  *r,
                   float  *sc,  float  *rowcnd,  float *colcnd, float
                   *amax, int *info) ;
    
    PURPOSE
         CGEEQU computes row and column scalings intended to  equili-
         brate an M-by-N matrix A and reduce its condition number.  R
         returns the row scale factors and C the  column  scale  fac-
         tors,  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 under-
                   flow, the matrix should be scaled.
    
         INFO      (output) INTEGER
                   = 0:  successful exit
                   < 0:  if INFO = -i, the i-th argument had an ille-
                   gal 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
    
    
    
    


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