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NAME DLANGE - return the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest abso- lute value of a real matrix A SYNOPSIS DOUBLE PRECISION FUNCTION DLANGE( NORM, M, N, A, LDA, WORK ) CHARACTER NORM INTEGER LDA, M, N DOUBLE PRECISION A( LDA, * ), WORK( * ) PURPOSE DLANGE returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real matrix A. DESCRIPTION DLANGE returns the value DLANGE = ( max(abs(A(i,j))), NORM = 'M' or 'm' ( ( norm1(A), NORM = '1', 'O' or 'o' ( ( normI(A), NORM = 'I' or 'i' ( ( normF(A), NORM = 'F', 'f', 'E' or 'e' 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 matrix norm. ARGUMENTS NORM (input) CHARACTER*1 Specifies the value to be returned in DLANGE as described above. M (input) INTEGER The number of rows of the matrix A. M >= 0. When M = 0, DLANGE is set to zero. N (input) INTEGER The number of columns of the matrix A. N >= 0. When N = 0, DLANGE is set to zero. A (input) DOUBLE PRECISION 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) DOUBLE PRECISION array, dimension (LWORK), where LWORK >= M when NORM = 'I'; otherwise, WORK is not referenced.