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