| 106 |
describe the orientations between the the tiles. |
describe the orientations between the the tiles. |
| 107 |
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|
| 108 |
The array {\em exch2\_neighbourId(a,T)} holds the tile number $T_{n}$ for each tile |
The array {\em exch2\_neighbourId(a,T)} holds the tile number $T_{n}$ for each tile |
| 109 |
{\em T}'s neighbor tile {\em a}, and {\em exch2\_opposingSend\_record(a,T)} holds |
{\em T}'s neighbor tile {\em a}. The neighbor tiles are indexed {\em 1,MAX\_NEIGHBOURS } |
| 110 |
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in the order right to left on the north then south edges, and then top to bottom on the east |
| 111 |
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and west edges. maybe throw in a fig here, eh? |
| 112 |
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|
| 113 |
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{\em exch2\_opposingSend\_record(a,T)} holds |
| 114 |
the index c in {\em exch2\_neighbourId(b,$T_{n}$)} that holds the tile number T. |
the index c in {\em exch2\_neighbourId(b,$T_{n}$)} that holds the tile number T. |
| 115 |
In other words, |
In other words, |
| 116 |
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|
| 117 |
\begin{verbatim} |
\begin{verbatim} |
| 118 |
exch2_neighbourId( exch2_opposingSend_record(a,T), exch2_neighbourId(a,T) ) = T |
exch2_neighbourId( exch2_opposingSend_record(a,T), |
| 119 |
|
exch2_neighbourId(a,T) ) = T |
| 120 |
\end{verbatim} |
\end{verbatim} |
| 121 |
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|
| 122 |
% {\em exch2\_neighbourId(exch2\_opposingSend\_record(a,T),exch2\_neighbourId(a,T))=T}. |
% {\em exch2\_neighbourId(exch2\_opposingSend\_record(a,T),exch2\_neighbourId(a,T))=T}. |
| 124 |
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|
| 125 |
This is to provide a backreference from the neighbor tiles. |
This is to provide a backreference from the neighbor tiles. |
| 126 |
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|
| 127 |
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The arrays {\em exch2\_pi }, {\em exch2\_pj }, {\em exch2\_oi }, |
| 128 |
|
{\em exch2\_oj }, {\em exch2\_oi\_f }, and {\em exch2\_oj\_f } specify |
| 129 |
|
the transformations in exchanges between the neighboring tiles. The dimensions |
| 130 |
|
of {\em exch2\_pi(t,N,T) } and {\em exch2\_pj(t,N,T) } are the neighbor ID |
| 131 |
|
{ \em N } and the tile number {\em T } as explained above, plus the transformation |
| 132 |
|
vector {\em t }, of length two. The first element of the transformation vector indicates |
| 133 |
|
the factor by which variables representing the same vector component of a tile |
| 134 |
|
will be multiplied, and the second element indicates the transform to the |
| 135 |
|
variable in the other direction. As an example, {\em exch2\_pi(1,N,T) } holds the |
| 136 |
|
transform of the i-component of a vector variable in tile {\em T } to the i-component of |
| 137 |
|
tile {\em T }'s neighbor {\em N }, and {\em exch2\_pi(2,N,T) } hold the component |
| 138 |
|
of neighbor {\em N }'s j-component. |
| 139 |
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|
| 140 |
|
Under the current cube topology, one of the two elements of {\em exch2\_pi } or {\em exch2\_pj } |
| 141 |
|
for a given tile {\em T } and neighbor {\em N } will be 0, reflecting the fact that |
| 142 |
|
the vector components are orthogonal. The other element will be 1 or -1, depending on whether |
| 143 |
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the components are indexed in the same or opposite directions. For example, the transform dimension |
| 144 |
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of the arrays for all tile neighbors on the same subdomain will be {\em [1 , 0] }, since all tiles on |
| 145 |
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the same subdomain are oriented identically. Vectors that correspond to the orthogonal dimension with the |
| 146 |
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same index direction will have {\em [0 , 1] }, whereas those in the opposite index direction will have |
| 147 |
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{\em [0 , -1] }. |
| 148 |
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| 149 |
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| 150 |
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| 151 |
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| 152 |
// |
// |
| 153 |
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