Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?lanhs
Returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of an upper Hessenberg matrix.
Syntax
valslanhs ( norm , n , a , lda , work )
valdlanhs ( norm , n , a , lda , work )
valclanhs ( norm , n , a , lda , work )
valzlanhs ( norm , n , a , lda , work )
Include Files
mkl.fi
Description
slanhs dlanhs clanhs zlanhs
The function ?lanhs returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a Hessenberg matrix A .
The value val returned by the function is:
val = max(abs(A_{ij})) , if norm = ‘M’ or ‘m’
= norm1 ( A ), if norm = ‘1’ or ‘O’ or ‘o’
= normI ( A ), if norm = ‘I’ or ‘i’
= normF ( A ), if norm = ‘F’ , ‘f’ , ‘E’ or ‘e’
where norm1 denotes the 1-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_{ij})) is not a consistent matrix norm.
Input Parameters
- norm
-
CHARACTER*1 . Specifies the value to be returned by the routine as described above.
- n
-
INTEGER . The order of the matrix A . n≥ 0 . When n = 0 , ?lanhs is set to zero.
- a
-
REAL for slanhs DOUBLE PRECISION for dlanhs COMPLEX for clanhs DOUBLE COMPLEX for zlanhs Array, DIMENSION ( lda , n ). The n -by- n upper Hessenberg matrix A ; the part of A below the first sub-diagonal is not referenced.
- lda
-
INTEGER . The leading dimension of the array a . lda≥ max(n,1) .
- work
-
REAL for slanhs and clanhs . DOUBLE PRECISION for dlange and zlange . Workspace array, DIMENSION (max(1,lwork)) , where lwork≥n when norm = 'I' ; otherwise, work is not referenced.
Output Parameters
- val
-
REAL for slanhs / clanhs DOUBLE PRECISION for dlanhs / zlanhs Value returned by the function.