cgbequ.f man page on Oracle

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cgbequ.f(3)			    LAPACK			   cgbequ.f(3)

       cgbequ.f -

       subroutine cgbequ (M, N, KL, KU, AB, LDAB, R, C, ROWCND, COLCND, AMAX,

Function/Subroutine Documentation
   subroutine cgbequ (integerM, integerN, integerKL, integerKU, complex,
       dimension( ldab, * )AB, integerLDAB, real, dimension( * )R, real,
       dimension( * )C, realROWCND, realCOLCND, realAMAX, integerINFO)


	    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
	    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.


		     KL is INTEGER
		     The number of subdiagonals within the band of A.  KL >= 0.


		     KU is INTEGER
		     The number of superdiagonals within the band of A.	 KU >= 0.


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


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


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


		     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

	   NAG Ltd.

	   November 2011

       Definition at line 154 of file cgbequ.f.

       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2			Tue Sep 25 2012			   cgbequ.f(3)

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