Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?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
valslangt ( norm , n , dl , d , du )
valdlangt ( norm , n , dl , d , du )
valclangt ( norm , n , dl , d , du )
valzlangt ( norm , n , dl , d , du )
Include Files
mkl.fi
Description
slangt dlangt clangt zlangt
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.