man clangt (Fonctions bibliothèques) - return the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a complex tridiagonal matrix A
NAME
CLANGT - return the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a complex tridiagonal matrix A
SYNOPSIS
- REAL FUNCTION
- CLANGT( NORM, N, DL, D, DU )
- CHARACTER NORM
- INTEGER N
- COMPLEX D( * ), DL( * ), DU( * )
PURPOSE
CLANGT 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 tridiagonal matrix A.
DESCRIPTION
CLANGT returns the value
CLANGT = ( 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 CLANGT as described above.
- N (input) INTEGER
- The order of the matrix A. N >= 0. When N = 0, CLANGT is set to zero.
- DL (input) COMPLEX array, dimension (N-1)
- The (n-1) sub-diagonal elements of A.
- D (input) COMPLEX array, dimension (N)
- The diagonal elements of A.
- DU (input) COMPLEX array, dimension (N-1)
- The (n-1) super-diagonal elements of A.