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In classic loop Do I =2,N Do J=2,N FI(I,J) =.25*(FI(I+1,J)+FI(I-1,J)+FI(I,J+1)+FI(I,J-1))
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We see spatial locality -- if (I,J) accessed so are neighboring points stored near (I,J) in memory
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Spatial locality is essential for distributed memory as ensures that after data decomposition, most data you need is stored in same processor and so communication is modest (surface over volume)
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Spatial locality also exploited by vector machines
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Temporal locality says that if you use FI(I,J) in one loop it is used in next J index value as FI(I,(J+1)-1)
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Temporal locality makes cache machines work well as ensures after a data value stored into cache, it is used multiple times
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