Visible to Intel only — GUID: GUID-CC129C60-4F39-44B8-B194-0A4E933C209F
Visible to Intel only — GUID: GUID-CC129C60-4F39-44B8-B194-0A4E933C209F
?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.
Syntax
val = slangt( norm, n, dl, d, du )
val = dlangt( norm, n, dl, d, du )
val = clangt( norm, n, dl, d, du )
val = zlangt( norm, n, dl, d, du )
Include Files
- mkl.fi
Description
The routine returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real/complex tridiagonal matrix A.
Input Parameters
- norm
-
CHARACTER*1. Specifies the value to be returned by the routine:
= 'M' or 'm': val = max(abs(Aij)), largest absolute value of the matrix A.
= '1' or 'O' or 'o': val = norm1(A), 1-norm of the matrix A (maximum column sum),
= 'I' or 'i': val = normI(A), infinity norm of the matrix A (maximum row sum),
= 'F', 'f', 'E' or 'e': val = normF(A), Frobenius norm of the matrix A (square root of sum of squares).
- n
-
INTEGER. The order of the matrix A. n≥ 0. When n = 0, ?langt is set to zero.
- dl, d, du
-
REAL for slangt
DOUBLE PRECISION for dlangt
COMPLEX for clangt
DOUBLE COMPLEX for zlangt
Arrays: dl (n-1), d (n), du (n-1).
The array dl contains the (n-1) sub-diagonal elements of A.
The array d contains the diagonal elements of A.
The array du contains the (n-1) super-diagonal elements of A.
Output Parameters
- val
-
REAL for slangt/clangt
DOUBLE PRECISION for dlangt/zlangt
Value returned by the function.