clantb (l)  Linux Man Pages
clantb: returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of an n by n triangular band matrix A, with ( k + 1 ) diagonals
NAME
CLANTB  returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of an n by n triangular band matrix A, with ( k + 1 ) diagonalsSYNOPSIS
 REAL FUNCTION
 CLANTB( NORM, UPLO, DIAG, N, K, AB, LDAB, WORK )
 CHARACTER DIAG, NORM, UPLO
 INTEGER K, LDAB, N
 REAL WORK( * )
 COMPLEX AB( LDAB, * )
PURPOSE
CLANTB returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of an n by n triangular band matrix A, with ( k + 1 ) diagonals.DESCRIPTION
CLANTB returns the valueCLANTB
ARGUMENTS
 NORM (input) CHARACTER*1
 Specifies the value to be returned in CLANTB as described above.
 UPLO (input) CHARACTER*1

Specifies whether the matrix A is upper or lower triangular.
= aqUaq: Upper triangular
= aqLaq: Lower triangular  DIAG (input) CHARACTER*1

Specifies whether or not the matrix A is unit triangular.
= aqNaq: Nonunit triangular
= aqUaq: Unit triangular  N (input) INTEGER
 The order of the matrix A. N >= 0. When N = 0, CLANTB is set to zero.
 K (input) INTEGER
 The number of superdiagonals of the matrix A if UPLO = aqUaq, or the number of subdiagonals of the matrix A if UPLO = aqLaq. K >= 0.
 AB (input) COMPLEX array, dimension (LDAB,N)
 The upper or lower triangular band matrix A, stored in the first k+1 rows of AB. The jth column of A is stored in the jth column of the array AB as follows: if UPLO = aqUaq, AB(k+1+ij,j) = A(i,j) for max(1,jk)<=i<=j; if UPLO = aqLaq, AB(1+ij,j) = A(i,j) for j<=i<=min(n,j+k). Note that when DIAG = aqUaq, the elements of the array AB corresponding to the diagonal elements of the matrix A are not referenced, but are assumed to be one.
 LDAB (input) INTEGER
 The leading dimension of the array AB. LDAB >= K+1.
 WORK (workspace) REAL array, dimension (MAX(1,LWORK)),

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