clange (l) - Linux Manuals

clange: returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a complex matrix A

NAME

CLANGE - returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a complex matrix A

SYNOPSIS

REAL FUNCTION

CLANGE( NORM, M, N, A, LDA, WORK )

    

CHARACTER NORM

    

INTEGER LDA, M, N

    

REAL WORK( * )

    

COMPLEX A( LDA, * )

PURPOSE

CLANGE returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a complex matrix A.

DESCRIPTION

CLANGE returns the value

CLANGE = ( max(abs(A(i,j))), NORM = aqMaq or aqmaq

      (

      ( norm1(A),         NORM = aq1aq, aqOaq or aqoaq

      (

      ( normI(A),         NORM = aqIaq or aqiaq

      (

      ( normF(A),         NORM = aqFaq, aqfaq, aqEaq or aqeaq where norm1 denotes the one norm of a matrix (maximum column sum), normI denotes the infinity norm of a matrix (maximum row sum) and normF denotes the Frobenius norm of a matrix (square root of sum of squares). Note that max(abs(A(i,j))) is not a consistent matrix norm.

ARGUMENTS

NORM (input) CHARACTER*1

Specifies the value to be returned in CLANGE as described above.

M (input) INTEGER

The number of rows of the matrix A. M >= 0. When M = 0, CLANGE is set to zero.

N (input) INTEGER

The number of columns of the matrix A. N >= 0. When N = 0, CLANGE is set to zero.

A (input) COMPLEX array, dimension (LDA,N)

The m by n matrix A.

LDA (input) INTEGER

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

WORK (workspace) REAL array, dimension (MAX(1,LWORK)),

where LWORK >= M when NORM = aqIaq; otherwise, WORK is not referenced.