dpoequb.f(3) [debian man page]

dpoequb.f(3)							      LAPACK							      dpoequb.f(3)

NAME

       dpoequb.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dpoequb (N, A, LDA, S, SCOND, AMAX, INFO)
	   DPOEQUB

Function/Subroutine Documentation
   subroutine dpoequb (integerN, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( * )S, double precisionSCOND,
       double precisionAMAX, integerINFO)
       DPOEQUB

       Purpose:

	    DPOEQU computes row and column scalings intended to equilibrate a
	    symmetric positive definite matrix A and reduce its condition number
	    (with respect to the two-norm).  S contains the scale factors,
	    S(i) = 1/sqrt(A(i,i)), chosen so that the scaled matrix B with
	    elements B(i,j) = S(i)*A(i,j)*S(j) has ones on the diagonal.  This
	    choice of S puts the condition number of B within a factor N of the
	    smallest possible condition number over all possible diagonal
	    scalings.

       Parameters:
	   N

		     N is INTEGER
		     The order of the matrix A.  N >= 0.

	   A

		     A is DOUBLE PRECISION array, dimension (LDA,N)
		     The N-by-N symmetric positive definite matrix whose scaling
		     factors are to be computed.  Only the diagonal elements of A
		     are referenced.

	   LDA

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

	   S

		     S is DOUBLE PRECISION array, dimension (N)
		     If INFO = 0, S contains the scale factors for A.

	   SCOND

		     SCOND is DOUBLE PRECISION
		     If INFO = 0, S contains the ratio of the smallest S(i) to
		     the largest S(i).	If SCOND >= 0.1 and AMAX is neither too
		     large nor too small, it is not worth scaling by S.

	   AMAX

		     AMAX is DOUBLE PRECISION
		     Absolute value of largest matrix element.	If AMAX is very
		     close to overflow or very close to underflow, the matrix
		     should be scaled.

	   INFO

		     INFO is INTEGER
		     = 0:  successful exit
		     < 0:  if INFO = -i, the i-th argument had an illegal value
		     > 0:  if INFO = i, the i-th diagonal element is nonpositive.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Definition at line 113 of file dpoequb.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.1							  Sun May 26 2013						      dpoequb.f(3)