Provided by: liblapack-doc_3.3.1-1_all

#### NAME

```       LAPACK-3 - DLA_PORCOND Estimate the Skeel condition number of op(A) * op2(C)  where op2 is
determined by CMODE as follows  CMODE = 1 op2(C) = C  CMODE = 0 op2(C) =  I   CMODE  =  -1
op2(C)  = inv(C)  The Skeel condition number cond(A) = norminf( |inv(A)||A| )  is computed
by computing scaling factors  R  such  that   diag(R)*A*op2(C)  is  row  equilibrated  and
computing the standard  infinity-norm condition number

```

#### SYNOPSIS

```       DOUBLE PRECISION FUNCTION  DLA_PORCOND(  UPLO,  N, A, LDA, AF, LDAF, CMODE, C, INFO, WORK,
IWORK )

IMPLICIT     NONE

CHARACTER    UPLO

INTEGER      N, LDA, LDAF, INFO, CMODE

DOUBLE       PRECISION A( LDA, * ), AF( LDAF, * ), WORK( * ), C( * )

INTEGER      IWORK( * )

```

#### PURPOSE

```          DLA_PORCOND Estimates the Skeel condition number of  op(A) * op2(C)
where op2 is determined by CMODE as follows
CMODE =  1    op2(C) = C
CMODE =  0    op2(C) = I
CMODE = -1    op2(C) = inv(C)
The Skeel condition number  cond(A) = norminf( |inv(A)||A| )
is computed by computing scaling factors R such that
diag(R)*A*op2(C) is row equilibrated and computing the standard
infinity-norm condition number.

```

#### ARGUMENTS

```        UPLO    (input) CHARACTER*1
= 'U':  Upper triangle of A is stored;
= 'L':  Lower triangle of A is stored.

N       (input) INTEGER
The number of linear equations, i.e., the order of the
matrix A.  N >= 0.

A       (input) DOUBLE PRECISION array, dimension (LDA,N)
On entry, the N-by-N matrix A.

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

AF      (input) DOUBLE PRECISION array, dimension (LDAF,N)
The triangular factor U or L from the Cholesky factorization
A = U**T*U or A = L*L**T, as computed by DPOTRF.

LDAF    (input) INTEGER
The leading dimension of the array AF.  LDAF >= max(1,N).

CMODE   (input) INTEGER
Determines op2(C) in the formula op(A) * op2(C) as follows:
CMODE =  1    op2(C) = C
CMODE =  0    op2(C) = I
CMODE = -1    op2(C) = inv(C)

C       (input) DOUBLE PRECISION array, dimension (N)
The vector C in the formula op(A) * op2(C).

INFO    (output) INTEGER
= 0:  Successful exit.
i > 0:  The ith argument is invalid.

WORK    (input) DOUBLE PRECISION array, dimension (3*N).
Workspace.

IWORK   (input) INTEGER array, dimension (N).
Workspace.

LAPACK routine (version 3.2.2)          April 2011                       DLA_PORCOND(3lapack)
```