?la_gercond_x

Computes the infinity norm condition number of op(A)*diag(x) for general matrices.

Syntax

call cla_gercond_x( trans, n, a, lda, af, ldaf, ipiv, x, info, work, rwork )

call zla_gercond_x( trans, n, a, lda, af, ldaf, ipiv, x, info, work, rwork )

• mkl.fi

Description

The function computes the infinity norm condition number of

op(A) * diag(x)

where the x is a COMPLEX vector for cla_gercond_x and a DOUBLE COMPLEX vector for zla_gercond_x.

Input Parameters

trans

CHARACTER*1. Must be 'N' or 'T' or 'C'.

Specifies the form of the system of equations:

If trans = 'N', the system has the form A*X = B (No transpose)

If trans = 'T', the system has the form AT*X = B (Transpose)

If trans = 'C', the system has the form AH*X = B (Conjugate Transpose = Transpose)

n

INTEGER. The number of linear equations, that is, the order of the matrix A; n 0.

a, af, x, work

COMPLEX for cla_gercond_x

DOUBLE COMPLEX for zla_gercond_x

Arrays:

a(lda,*) contains the original general n-by-n matrix A.

af(ldaf,*) contains the factors L and U from the factorization A=P*L*U as returned by ?getrf.

x, DIMENSIONn. The vector x in the formula op(A) * diag(x).

work is a workspace array of DIMENSION (2*n).

The second dimension of a and af must be at least max(1, n).

lda

INTEGER. The leading dimension of the array a. ldamax(1,n).

ldaf

INTEGER. The leading dimension of af. ldafmax(1,n).

ipiv

INTEGER.

Array with DIMENSIONn. The pivot indices from the factorization A = P*L*U as computed by ?getrf. Row i of the matrix was interchanged with row ipiv(i).

rwork

REAL for cla_gercond_x

DOUBLE PRECISION for zla_gercond_x

Array rwork with DIMENSIONn is a workspace.

Output Parameters

info

INTEGER.

If info = 0, the execution is successful.

If i > 0, the i-th parameter is invalid.