cgecon.f - Man Page

SRC/cgecon.f

Synopsis

Functions/Subroutines

subroutine cgecon (norm, n, a, lda, anorm, rcond, work, rwork, info)
CGECON

Function/Subroutine Documentation

subroutine cgecon (character norm, integer n, complex, dimension( lda, * ) a, integer lda, real anorm, real rcond, complex, dimension( * ) work, real, dimension( * ) rwork, integer info)

CGECON

Purpose:

``` CGECON estimates the reciprocal of the condition number of a general
complex matrix A, in either the 1-norm or the infinity-norm, using
the LU factorization computed by CGETRF.

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)) ).```
Parameters

NORM

```          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

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

A

```          A is COMPLEX array, dimension (LDA,N)
The factors L and U from the factorization A = P*L*U
as computed by CGETRF.```

LDA

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

ANORM

```          ANORM is REAL
If NORM = '1' or 'O', the 1-norm of the original matrix A.
If NORM = 'I', the infinity-norm of the original matrix A.```

RCOND

```          RCOND is REAL
The reciprocal of the condition number of the matrix A,
computed as RCOND = 1/(norm(A) * norm(inv(A))).```

WORK

`          WORK is COMPLEX array, dimension (2*N)`

RWORK

`          RWORK is REAL array, dimension (2*N)`

INFO

```          INFO is INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value.
NaNs are illegal values for ANORM, and they propagate to
the output parameter RCOND.
Infinity is illegal for ANORM, and it propagates to the output
parameter RCOND as 0.
= 1:  if RCOND = NaN, or
RCOND = Inf, or
the computed norm of the inverse of A is 0.
In the latter, RCOND = 0 is returned.```
Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 130 of file cgecon.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

The man page cgecon(3) is an alias of cgecon.f(3).

Tue Nov 28 2023 12:08:41 Version 3.12.0 LAPACK