cgbequ man page on YellowDog

Man page or keyword search:  
man Server   18644 pages
apropos Keyword Search (all sections)
Output format
YellowDog logo
[printable version]

CGBEQU(l)			       )			     CGBEQU(l)

NAME
       CGBEQU  - compute row and column scalings intended to equilibrate an M-
       by-N band matrix A and reduce its condition number

SYNOPSIS
       SUBROUTINE CGBEQU( M, N, KL, KU, AB, LDAB, R, C, ROWCND, COLCND,	 AMAX,
			  INFO )

	   INTEGER	  INFO, KL, KU, LDAB, M, N

	   REAL		  AMAX, COLCND, ROWCND

	   REAL		  C( * ), R( * )

	   COMPLEX	  AB( LDAB, * )

PURPOSE
       CGBEQU  computes	 row and column scalings intended to equilibrate an M-
       by-N band 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 num‐
       ber 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.

       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) COMPLEX array, dimension (LDAB,N)
	       The band matrix A, stored in rows 1 to KL+KU+1.	The j-th  col‐
	       umn  of	A is stored in the j-th column of the array AB as fol‐
	       lows: AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl).

       LDAB    (input) INTEGER
	       The leading dimension of the array AB.  LDAB >= KL+KU+1.

       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 version 3.0		 15 June 2000			     CGBEQU(l)
[top]

List of man pages available for YellowDog

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net