# Name

HPL_dlange Compute ||A||.

# Synopsis

`#include "hpl.h"`

`double` `HPL_dlange(` `const HPL_T_NORM` `NORM`, `const int` `M`, `const int` `N`, `const double *` `A`, `const int` `LDA` `);`

# Description

HPL_dlange returns the value of the one norm, or the infinity norm, or the element of largest absolute value of a 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

```NORM    (local input)                 const HPL_T_NORM
On entry,  NORM  specifies  the  value to be returned by this
function as described above.
```
```M       (local input)                 const int
On entry,  M  specifies  the number  of rows of the matrix A.
M must be at least zero.
```
```N       (local input)                 const int
On entry,  N specifies the number of columns of the matrix A.
N must be at least zero.
```
```A       (local input)                 const double *
On entry,  A  points to an  array of dimension  (LDA,N), that
contains the 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,M).
```

# Example

`#include "hpl.h"`

```int main(int argc, char *argv[])
{
double a[2*2];
a = 1.0; a = 3.0; a = 2.0; a = 4.0;
norm = HPL_dlange( HPL_NORM_I, 2, 2, a, 2 );
printf("norm=%f\n", norm);
exit(0); return(0);
}
```