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| 2 | 1 | equemene | <HEAD>
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| 3 | 1 | equemene | <TITLE>HPL_dgemv HPL 2.0 Library Functions September 10, 2008</TITLE> |
| 4 | 1 | equemene | </HEAD>
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| 5 | 1 | equemene | |
| 6 | 1 | equemene | <BODY BGCOLOR="WHITE" TEXT = "#000000" LINK = "#0000ff" VLINK = "#000099" |
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| 8 | 1 | equemene | |
| 9 | 1 | equemene | <H1>Name</H1> |
| 10 | 1 | equemene | <B>HPL_dgemv</B> y := beta * y + alpha * op(A) * x. |
| 11 | 1 | equemene | |
| 12 | 1 | equemene | <H1>Synopsis</H1> |
| 13 | 1 | equemene | <CODE>#include "hpl.h"</CODE><BR><BR> |
| 14 | 1 | equemene | <CODE>void</CODE> |
| 15 | 1 | equemene | <CODE>HPL_dgemv(</CODE> |
| 16 | 1 | equemene | <CODE>const enum HPL_ORDER</CODE> |
| 17 | 1 | equemene | <CODE>ORDER</CODE>, |
| 18 | 1 | equemene | <CODE>const enum HPL_TRANS</CODE> |
| 19 | 1 | equemene | <CODE>TRANS</CODE>, |
| 20 | 1 | equemene | <CODE>const int</CODE> |
| 21 | 1 | equemene | <CODE>M</CODE>, |
| 22 | 1 | equemene | <CODE>const int</CODE> |
| 23 | 1 | equemene | <CODE>N</CODE>, |
| 24 | 1 | equemene | <CODE>const double</CODE> |
| 25 | 1 | equemene | <CODE>ALPHA</CODE>, |
| 26 | 1 | equemene | <CODE>const double *</CODE> |
| 27 | 1 | equemene | <CODE>A</CODE>, |
| 28 | 1 | equemene | <CODE>const int</CODE> |
| 29 | 1 | equemene | <CODE>LDA</CODE>, |
| 30 | 1 | equemene | <CODE>const double *</CODE> |
| 31 | 1 | equemene | <CODE>X</CODE>, |
| 32 | 1 | equemene | <CODE>const int</CODE> |
| 33 | 1 | equemene | <CODE>INCX</CODE>, |
| 34 | 1 | equemene | <CODE>const double</CODE> |
| 35 | 1 | equemene | <CODE>BETA</CODE>, |
| 36 | 1 | equemene | <CODE>double *</CODE> |
| 37 | 1 | equemene | <CODE>Y</CODE>, |
| 38 | 1 | equemene | <CODE>const int</CODE> |
| 39 | 1 | equemene | <CODE>INCY</CODE> |
| 40 | 1 | equemene | <CODE>);</CODE> |
| 41 | 1 | equemene | |
| 42 | 1 | equemene | <H1>Description</H1> |
| 43 | 1 | equemene | <B>HPL_dgemv</B> |
| 44 | 1 | equemene | performs one of the matrix-vector operations |
| 45 | 1 | equemene | |
| 46 | 1 | equemene | y := alpha * op( A ) * x + beta * y, |
| 47 | 1 | equemene | |
| 48 | 1 | equemene | where op( X ) is one of |
| 49 | 1 | equemene | |
| 50 | 1 | equemene | op( X ) = X or op( X ) = X^T. |
| 51 | 1 | equemene | |
| 52 | 1 | equemene | where alpha and beta are scalars, x and y are vectors and A is an m |
| 53 | 1 | equemene | by n matrix. |
| 54 | 1 | equemene | |
| 55 | 1 | equemene | <H1>Arguments</H1> |
| 56 | 1 | equemene | <PRE>
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| 57 | 1 | equemene | ORDER (local input) const enum HPL_ORDER |
| 58 | 1 | equemene | On entry, ORDER specifies the storage format of the operands |
| 59 | 1 | equemene | as follows: |
| 60 | 1 | equemene | ORDER = HplRowMajor, |
| 61 | 1 | equemene | ORDER = HplColumnMajor. |
| 62 | 1 | equemene | </PRE>
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| 63 | 1 | equemene | <PRE>
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| 64 | 1 | equemene | TRANS (local input) const enum HPL_TRANS |
| 65 | 1 | equemene | On entry, TRANS specifies the operation to be performed as |
| 66 | 1 | equemene | follows: |
| 67 | 1 | equemene | TRANS = HplNoTrans y := alpha*A *x + beta*y, |
| 68 | 1 | equemene | TRANS = HplTrans y := alpha*A^T*x + beta*y. |
| 69 | 1 | equemene | </PRE>
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| 70 | 1 | equemene | <PRE>
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| 71 | 1 | equemene | M (local input) const int |
| 72 | 1 | equemene | On entry, M specifies the number of rows of the matrix A. |
| 73 | 1 | equemene | M must be at least zero. |
| 74 | 1 | equemene | </PRE>
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| 75 | 1 | equemene | <PRE>
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| 76 | 1 | equemene | N (local input) const int |
| 77 | 1 | equemene | On entry, N specifies the number of columns of the matrix A. |
| 78 | 1 | equemene | N must be at least zero. |
| 79 | 1 | equemene | </PRE>
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| 80 | 1 | equemene | <PRE>
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| 81 | 1 | equemene | ALPHA (local input) const double |
| 82 | 1 | equemene | On entry, ALPHA specifies the scalar alpha. When ALPHA is |
| 83 | 1 | equemene | supplied as zero then A and X need not be set on input. |
| 84 | 1 | equemene | </PRE>
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| 85 | 1 | equemene | <PRE>
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| 86 | 1 | equemene | A (local input) const double * |
| 87 | 1 | equemene | On entry, A points to an array of size equal to or greater |
| 88 | 1 | equemene | than LDA * n. Before entry, the leading m by n part of the |
| 89 | 1 | equemene | array A must contain the matrix coefficients. |
| 90 | 1 | equemene | </PRE>
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| 91 | 1 | equemene | <PRE>
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| 92 | 1 | equemene | LDA (local input) const int |
| 93 | 1 | equemene | On entry, LDA specifies the leading dimension of A as |
| 94 | 1 | equemene | declared in the calling (sub) program. LDA must be at |
| 95 | 1 | equemene | least MAX(1,m). |
| 96 | 1 | equemene | </PRE>
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| 97 | 1 | equemene | <PRE>
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| 98 | 1 | equemene | X (local input) const double * |
| 99 | 1 | equemene | On entry, X is an incremented array of dimension at least |
| 100 | 1 | equemene | ( 1 + ( n - 1 ) * abs( INCX ) ) that contains the vector x. |
| 101 | 1 | equemene | </PRE>
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| 102 | 1 | equemene | <PRE>
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| 103 | 1 | equemene | INCX (local input) const int |
| 104 | 1 | equemene | On entry, INCX specifies the increment for the elements of X. |
| 105 | 1 | equemene | INCX must not be zero. |
| 106 | 1 | equemene | </PRE>
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| 107 | 1 | equemene | <PRE>
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| 108 | 1 | equemene | BETA (local input) const double |
| 109 | 1 | equemene | On entry, BETA specifies the scalar beta. When ALPHA is |
| 110 | 1 | equemene | supplied as zero then Y need not be set on input. |
| 111 | 1 | equemene | </PRE>
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| 112 | 1 | equemene | <PRE>
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| 113 | 1 | equemene | Y (local input/output) double * |
| 114 | 1 | equemene | On entry, Y is an incremented array of dimension at least |
| 115 | 1 | equemene | ( 1 + ( n - 1 ) * abs( INCY ) ) that contains the vector y. |
| 116 | 1 | equemene | Before entry with BETA non-zero, the incremented array Y must |
| 117 | 1 | equemene | contain the vector y. On exit, Y is overwritten by the |
| 118 | 1 | equemene | updated vector y. |
| 119 | 1 | equemene | </PRE>
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| 120 | 1 | equemene | <PRE>
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| 121 | 1 | equemene | INCY (local input) const int |
| 122 | 1 | equemene | On entry, INCY specifies the increment for the elements of Y. |
| 123 | 1 | equemene | INCY must not be zero. |
| 124 | 1 | equemene | </PRE>
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| 125 | 1 | equemene | |
| 126 | 1 | equemene | <H1>Example</H1> |
| 127 | 1 | equemene | <CODE>#include "hpl.h"</CODE><BR><BR> |
| 128 | 1 | equemene | <PRE>
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| 129 | 1 | equemene | int main(int argc, char *argv[]) |
| 130 | 1 | equemene | {
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| 131 | 1 | equemene | double a[2*2], x[2], y[2]; |
| 132 | 1 | equemene | a[0] = 1.0; a[1] = 2.0; a[2] = 3.0; a[3] = 3.0; |
| 133 | 1 | equemene | x[0] = 2.0; x[1] = 1.0; y[2] = 1.0; y[3] = 2.0; |
| 134 | 1 | equemene | HPL_dgemv( HplColumnMajor, HplNoTrans, 2, 2, 2.0, |
| 135 | 1 | equemene | a, 2, x, 1, -1.0, y, 1 ); |
| 136 | 1 | equemene | printf("y=[%f,%f]\n", y[0], y[1]);
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| 137 | 1 | equemene | exit(0); return(0); |
| 138 | 1 | equemene | } |
| 139 | 1 | equemene | </PRE>
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| 140 | 1 | equemene | |
| 141 | 1 | equemene | <H1>See Also</H1> |
| 142 | 1 | equemene | <A HREF="HPL_dger.html">HPL_dger</A>, |
| 143 | 1 | equemene | <A HREF="HPL_dtrsv.html">HPL_dtrsv</A>. |
| 144 | 1 | equemene | |
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