.TH SLANST 1 "November 2006" " LAPACK auxiliary routine (version 3.1) " " LAPACK auxiliary routine (version 3.1) " .SH NAME SLANST - the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real symmetric tridiagonal matrix A .SH SYNOPSIS .TP 14 REAL FUNCTION SLANST( NORM, N, D, E ) .TP 14 .ti +4 CHARACTER NORM .TP 14 .ti +4 INTEGER N .TP 14 .ti +4 REAL D( * ), E( * ) .SH PURPOSE SLANST 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 symmetric tridiagonal matrix A. .SH DESCRIPTION SLANST returns the value .br SLANST = ( max(abs(A(i,j))), NORM = \(aqM\(aq or \(aqm\(aq .br ( .br ( norm1(A), NORM = \(aq1\(aq, \(aqO\(aq or \(aqo\(aq .br ( .br ( normI(A), NORM = \(aqI\(aq or \(aqi\(aq .br ( .br ( normF(A), NORM = \(aqF\(aq, \(aqf\(aq, \(aqE\(aq or \(aqe\(aq 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. .SH ARGUMENTS .TP 8 NORM (input) CHARACTER*1 Specifies the value to be returned in SLANST as described above. .TP 8 N (input) INTEGER The order of the matrix A. N >= 0. When N = 0, SLANST is set to zero. .TP 8 D (input) REAL array, dimension (N) The diagonal elements of A. .TP 8 E (input) REAL array, dimension (N-1) The (n-1) sub-diagonal or super-diagonal elements of A.