p?lanhs

Developer Reference for Intel® oneAPI Math Kernel Library for C

Download PDF

ID 766684

Date 4/28/2026

Version

Public

p?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

floatpslanhs ( char*norm , MKL_INT*n , float*a , MKL_INT*ia , MKL_INT*ja , MKL_INT*desca , float*work );

doublepdlanhs ( char*norm , MKL_INT*n , double*a , MKL_INT*ia , MKL_INT*ja , MKL_INT*desca , double*work );

floatpclanhs ( char*norm , MKL_INT*n , MKL_Complex8*a , MKL_INT*ia , MKL_INT*ja , MKL_INT*desca , float*work );

doublepzlanhs ( char*norm , MKL_INT*n , MKL_Complex16*a , MKL_INT*ia , MKL_INT*ja , MKL_INT*desca , double*work );

Include Files

mkl_scalapack.h

Description

pslanhs pdlanhs pclanhs pzlanhs The p?lanhs routine function returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of an upper Hessenberg distributed matrix sub(A) = A(ia:ia+m-1, ja:ja+n-1) .

Input Parameters

norm

Specifies the value to be returned by the function :

= ‘M’ or ‘m’: val = max(abs(A_{ij})) , 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

(global)

a

(local). REAL for pslanhs DOUBLE PRECISION for pdlanhs COMPLEX for pclanhs COMPLEX*16 for pzlanhs.

Pointer into the local memory to an array of size (lld_a, LOCc(ja+n-1))lld_a * LOCc(ja+n-1) containing the local pieces of the distributed matrix sub( A ).

ia , ja

(global)

The row and column indices in the global matrix A indicating the first row and the first column of the matrix sub( A ), respectively.

desca

(global and local) array of size dlen_ . The array descriptor for the distributed matrix A.

work

(local). REAL for pslanhs DOUBLE PRECISION for pdlanhs COMPLEX for pclanhs COMPLEX*16 for pzlanh . Array of size lwork . lwork ≥ 0 if norm = ‘M’ or ‘m’ (not referenced), nq 0 if norm = ‘1’, ‘O’ or ‘o’ , mp 0 if norm = ‘I’ or ‘i’ , 0 if norm = 'F' , ‘f’ , ‘E’ or ‘e’ (not referenced), where iroffa = mod ( ia -1, mb_a ), icoffa = mod ( ja -1, nb_a ), iarow = indxg2p ( ia , mb_a , myrow , rsrc_a , nprow ), iacol = indxg2p ( ja , nb_a , mycol , csrc_a , npcol ), mp 0 = numroc ( m + iroffa , mb_a , myrow , iarow , nprow ), nq 0 = numroc ( n + icoffa , nb_a , mycol , iacol , npcol ),

indxg2p and numroc are ScaLAPACK tool functions ; myrow , imycol , nprow , and npcol can be determined by calling the function blacs_gridinfo .

Output Parameters

val: The value returned by the function.

NOTE:

Overview

Select Your Language

Using Intel.com Search

Quick Links

Recent Searches

Advanced Search

Only search in

Developer Reference for Intel® oneAPI Math Kernel Library for C

p?lanhs

Syntax

Include Files

Description

Input Parameters

Output Parameters