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recode procedural algorithm to faster functional module


Can someone please help me recode this Module so it is less procedural 
and hopefully runs a lot faster. The Lists V1 and V2 represent two time  
series with 'bricks' laid out along them. The Bricks have varying length 
set by v[[i]][[1]] and v[[i]][[2]] and the idea is to count the number  
of times there is an overlap. I can only see the dumb procedural way of 
taking each brick and checking if it overlaps in time with another! 
  


Concurrence[v1_List, v2_List,nsim_]:=Module [

{k=1,c=0},
Do[
Do[
Which[
v1[[i]][[1]] == v2[[k]][[1]], c=c+1,
v1[[i]][[1]] < v2[[k]][[1]] && v1[[i]][[2]] > v2[[k]][[1]], c=c+1,
v1[[i]][[1]] > v2[[k]][[1]] && v1[[i]][[1]] < v2[[k]][[2]], c=c+1
];
(*Write[ strm1, {v1[[i]][[1]],v2[[i]][[1]],c}];*)
, {i,1,nsim}
], {k,1,nsim}
];
c
]

I've have a PowerPoint illustration if this is unclear and can e-mail it.

thanks
Robert Prince-Wright


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