root / www / HPL_dlange.html
Historique | Voir | Annoter | Télécharger (2,34 ko)
| 1 |
<HTML>
|
|---|---|
| 2 |
<HEAD>
|
| 3 |
<TITLE>HPL_dlange HPL 2.0 Library Functions September 10, 2008</TITLE> |
| 4 |
</HEAD>
|
| 5 |
|
| 6 |
<BODY BGCOLOR="WHITE" TEXT = "#000000" LINK = "#0000ff" VLINK = "#000099" |
| 7 |
ALINK = "#ffff00"> |
| 8 |
|
| 9 |
<H1>Name</H1> |
| 10 |
<B>HPL_dlange</B> Compute ||A||. |
| 11 |
|
| 12 |
<H1>Synopsis</H1> |
| 13 |
<CODE>#include "hpl.h"</CODE><BR><BR> |
| 14 |
<CODE>double</CODE> |
| 15 |
<CODE>HPL_dlange(</CODE> |
| 16 |
<CODE>const HPL_T_NORM</CODE> |
| 17 |
<CODE>NORM</CODE>, |
| 18 |
<CODE>const int</CODE> |
| 19 |
<CODE>M</CODE>, |
| 20 |
<CODE>const int</CODE> |
| 21 |
<CODE>N</CODE>, |
| 22 |
<CODE>const double *</CODE> |
| 23 |
<CODE>A</CODE>, |
| 24 |
<CODE>const int</CODE> |
| 25 |
<CODE>LDA</CODE> |
| 26 |
<CODE>);</CODE> |
| 27 |
|
| 28 |
<H1>Description</H1> |
| 29 |
<B>HPL_dlange</B> |
| 30 |
returns the value of the one norm, or the infinity norm, |
| 31 |
or the element of largest absolute value of a matrix A: |
| 32 |
|
| 33 |
max(abs(A(i,j))) when NORM = HPL_NORM_A, |
| 34 |
norm1(A), when NORM = HPL_NORM_1, |
| 35 |
normI(A), when NORM = HPL_NORM_I, |
| 36 |
|
| 37 |
where norm1 denotes the one norm of a matrix (maximum column sum) and |
| 38 |
normI denotes the infinity norm of a matrix (maximum row sum). Note |
| 39 |
that max(abs(A(i,j))) is not a matrix norm. |
| 40 |
|
| 41 |
<H1>Arguments</H1> |
| 42 |
<PRE>
|
| 43 |
NORM (local input) const HPL_T_NORM |
| 44 |
On entry, NORM specifies the value to be returned by this |
| 45 |
function as described above. |
| 46 |
</PRE>
|
| 47 |
<PRE>
|
| 48 |
M (local input) const int |
| 49 |
On entry, M specifies the number of rows of the matrix A. |
| 50 |
M must be at least zero. |
| 51 |
</PRE>
|
| 52 |
<PRE>
|
| 53 |
N (local input) const int |
| 54 |
On entry, N specifies the number of columns of the matrix A. |
| 55 |
N must be at least zero. |
| 56 |
</PRE>
|
| 57 |
<PRE>
|
| 58 |
A (local input) const double * |
| 59 |
On entry, A points to an array of dimension (LDA,N), that |
| 60 |
contains the matrix A. |
| 61 |
</PRE>
|
| 62 |
<PRE>
|
| 63 |
LDA (local input) const int |
| 64 |
On entry, LDA specifies the leading dimension of the array A. |
| 65 |
LDA must be at least max(1,M). |
| 66 |
</PRE>
|
| 67 |
|
| 68 |
<H1>Example</H1> |
| 69 |
<CODE>#include "hpl.h"</CODE><BR><BR> |
| 70 |
<PRE>
|
| 71 |
int main(int argc, char *argv[]) |
| 72 |
{
|
| 73 |
double a[2*2]; |
| 74 |
a[0] = 1.0; a[1] = 3.0; a[2] = 2.0; a[3] = 4.0; |
| 75 |
norm = HPL_dlange( HPL_NORM_I, 2, 2, a, 2 ); |
| 76 |
printf("norm=%f\n", norm);
|
| 77 |
exit(0); return(0); |
| 78 |
} |
| 79 |
</PRE>
|
| 80 |
|
| 81 |
<H1>See Also</H1> |
| 82 |
<A HREF="HPL_dlaprnt.html">HPL_dlaprnt</A>, |
| 83 |
<A HREF="HPL_fprintf.html">HPL_fprintf</A>. |
| 84 |
|
| 85 |
</BODY>
|
| 86 |
</HTML>
|