HPL_dlange - Man Page
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[0] = 1.0; a[1] = 3.0; a[2] = 2.0; a[3] = 4.0;
norm = HPL_dlange( HPL_NORM_I, 2, 2, a, 2 );
printf("norm=%f\n", norm);
exit(0); return(0);
}
See Also
HPL_dlaprnt (3), HPL_fprintf (3).