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template<typename T>
T langt(char *norm, integer *n, T *dl, T *d, T *du)# LANGT returns the value of the 1-norm, Frobenius norm, infinity-norm,
or the largest absolute value of any element of a general tridiagonal matrix.
Purpose:
LANGT 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 tridiagonal matrix A. SLANGT = (fla_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 fla_max(abs(A(i,j))) is not a consistent matrix norm.
- Parameters:
NORM – [in]
NORM is CHARACTER*1
Specifies the value to be returned in SLANGT as described above.
N – [in]
N is INTEGER
The order of the matrix A. N >= 0. When N = 0, SLANGT is set to zero.
DL – [in]
DL is REAL array, dimension (N-1)
The (n-1) sub-diagonal elements of A.
D – [in]
D is REAL array, dimension (N)
The diagonal elements of A.
DU – [in]
DU is REAL array, dimension (N-1)
The (n-1) super-diagonal elements of A.
- Returns:
Returns the value of norm.