LAPACK  3.5.0
LAPACK: Linear Algebra PACKage
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dgecon.f File Reference

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subroutine dgecon (NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK, INFO)
 DGECON More...

Function/Subroutine Documentation

subroutine dgecon ( character  NORM,
integer  N,
double precision, dimension( lda, * )  A,
integer  LDA,
double precision  ANORM,
double precision  RCOND,
double precision, dimension( * )  WORK,
integer, dimension( * )  IWORK,
integer  INFO 


Download DGECON + dependencies [TGZ] [ZIP] [TXT]
 DGECON estimates the reciprocal of the condition number of a general
 real matrix A, in either the 1-norm or the infinity-norm, using
 the LU factorization computed by DGETRF.

 An estimate is obtained for norm(inv(A)), and the reciprocal of the
 condition number is computed as
    RCOND = 1 / ( norm(A) * norm(inv(A)) ).
          NORM is CHARACTER*1
          Specifies whether the 1-norm condition number or the
          infinity-norm condition number is required:
          = '1' or 'O':  1-norm;
          = 'I':         Infinity-norm.
          N is INTEGER
          The order of the matrix A.  N >= 0.
          A is DOUBLE PRECISION array, dimension (LDA,N)
          The factors L and U from the factorization A = P*L*U
          as computed by DGETRF.
          LDA is INTEGER
          The leading dimension of the array A.  LDA >= max(1,N).
          If NORM = '1' or 'O', the 1-norm of the original matrix A.
          If NORM = 'I', the infinity-norm of the original matrix A.
          The reciprocal of the condition number of the matrix A,
          computed as RCOND = 1/(norm(A) * norm(inv(A))).
          WORK is DOUBLE PRECISION array, dimension (4*N)
          IWORK is INTEGER array, dimension (N)
          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
November 2011

Definition at line 124 of file dgecon.f.

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