# HPL_pdlange man page

HPL_pdlange — Compute ||A||.

## Synopsis

**#include "hpl.h"****double HPL_pdlange( const HPL_T_grid *** *GRID*, **const HPL_T_NORM** *NORM*, **const int** *M*, **const int** *N*, **const int** *NB*, **const double *** *A*, **const int** *LDA* **);**

## Description

**HPL_pdlange** returns the value of the one norm, or the infinity norm, or the element of largest absolute value of a distributed matrix A:

max(abs(A(i,j))) when NORM = HPL_NORM_A,

norm1(A), when NORM = HPL_NORM_1,

normI(A), when NORM = HPL_NORM_I,

where norm1 denotes the one norm of a matrix (maximum column sum) and normI denotes the infinity norm of a matrix (maximum row sum). Note that max(abs(A(i,j))) is not a matrix norm.

## Arguments

- GRID (local input) const HPL_T_grid *
- On entry, GRID points to the data structure containing the process grid information.
- NORM (global input) const HPL_T_NORM
- On entry, NORM specifies the value to be returned by this function as described above.
- M (global input) const int
- On entry, M specifies the number of rows of the matrix A. M must be at least zero.
- N (global input) const int
- On entry, N specifies the number of columns of the matrix A. N must be at least zero.
- NB (global input) const int
- On entry, NB specifies the blocking factor used to partition and distribute the matrix. NB must be larger than one.
- A (local input) const double *
- On entry, A points to an array of dimension (LDA,LocQ(N)), that contains the local pieces of the distributed matrix A.
- LDA (local input) const int
- On entry, LDA specifies the leading dimension of the array A. LDA must be at least max(1,LocP(M)).

## See Also

**HPL_pdlaprnt** (3), **HPL_fprintf** (3).