LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
REAL function  clantb (NORM, UPLO, DIAG, N, K, AB, LDAB, WORK) 
CLANTB returns the value of the 1norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a triangular band matrix. 
REAL function clantb  (  character  NORM, 
character  UPLO,  
character  DIAG,  
integer  N,  
integer  K,  
complex, dimension( ldab, * )  AB,  
integer  LDAB,  
real, dimension( * )  WORK  
) 
CLANTB returns the value of the 1norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a triangular band matrix.
Download CLANTB + dependencies [TGZ] [ZIP] [TXT]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.
CLANTB = ( 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 consistent matrix norm.
[in]  NORM  NORM is CHARACTER*1 Specifies the value to be returned in CLANTB as described above. 
[in]  UPLO  UPLO is CHARACTER*1 Specifies whether the matrix A is upper or lower triangular. = 'U': Upper triangular = 'L': Lower triangular 
[in]  DIAG  DIAG is CHARACTER*1 Specifies whether or not the matrix A is unit triangular. = 'N': Nonunit triangular = 'U': Unit triangular 
[in]  N  N is INTEGER The order of the matrix A. N >= 0. When N = 0, CLANTB is set to zero. 
[in]  K  K is INTEGER The number of superdiagonals of the matrix A if UPLO = 'U', or the number of subdiagonals of the matrix A if UPLO = 'L'. K >= 0. 
[in]  AB  AB is 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 = 'U', AB(k+1+ij,j) = A(i,j) for max(1,jk)<=i<=j; if UPLO = 'L', AB(1+ij,j) = A(i,j) for j<=i<=min(n,j+k). Note that when DIAG = 'U', the elements of the array AB corresponding to the diagonal elements of the matrix A are not referenced, but are assumed to be one. 
[in]  LDAB  LDAB is INTEGER The leading dimension of the array AB. LDAB >= K+1. 
[out]  WORK  WORK is REAL array, dimension (MAX(1,LWORK)), where LWORK >= N when NORM = 'I'; otherwise, WORK is not referenced. 
Definition at line 141 of file clantb.f.