recode procedural algorithm to faster functional module

• To: mathgroup at smc.vnet.net
• Subject: [mg44034] recode procedural algorithm to faster functional module
• From: "Prince-Wright, Robert G SEPCO" <robert.prince-wright at shell.com>
• Date: Sat, 18 Oct 2003 03:12:35 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```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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