table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/cpoequ.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/cpoequ.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/cpoequ.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine CPOEQU (n, a, lda, s, scond, amax, info)
CPOEQU
Function/Subroutine Documentation¶
subroutine CPOEQU (integer n, complex, dimension( lda, * ) a, integer lda, real, dimension( * ) s, real scond, real amax, integer info)¶
CPOEQU
Purpose:
!> !> CPOEQU computes row and column scalings intended to equilibrate a !> Hermitian 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 COMPLEX array, dimension (LDA,N) !> The N-by-N Hermitian 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 REAL array, dimension (N) !> If INFO = 0, S contains the scale factors for A. !>
SCOND
!> SCOND is REAL !> 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 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
!> 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.
Definition at line 112 of file cpoequ.f.
Author¶
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Version 3.12.0 | LAPACK |