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MathGroup Archive 2000

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RE: bug with Compile ?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg26399] RE: [mg26374] bug with Compile ?
  • From: "David Park" <djmp at earthlink.net>
  • Date: Wed, 20 Dec 2000 00:21:27 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Jean-Marie,

Defining your function in two steps seems to work.

EuclidianDistance5 = Compile[{{p, _Real, 1}, 
    {q, _Real, 1}}, With[{m = p - q}, Sqrt[m . m]]]
CompiledFunction[]

EuclidianDistance5a[p_List, q_List] := 
  Check[EuclidianDistance5[p, q], $Failed]

EuclidianDistance5a[{2, 3, 4}, {1, 2, 3}]
1.73205

EuclidianDistance5a[{2, 3, 4}, {1, 2, 3, 4}]
CompiledFunction::"cflist": "Non-tensor object generated; proceeding with \
uncompiled evaluation."

Thread::"tdlen": "Objects of unequal length in \!\(\(\({2, 3, 4}\)\) + \
\(\({\(\(-1\)\), \(\(-2\)\), \(\(-3\)\), \(\(-4\)\)}\)\)\) cannot be \
combined."
$Failed

Do[EuclidianDistance1[{2, 3, 4}, {1, 2, 3}], {10000}] // Timing
{0.87 Second, Null}

Do[EuclidianDistance5a[{2, 3, 4}, {1, 2, 3}], {10000}] // Timing
{0.22 Second, Null}

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/ 

> From: Jean-Marie THOMAS [mailto:jmt at agat.net]
To: mathgroup at smc.vnet.net
> $Version : "4.0 for Linux (April 21, 1999)"
> 
> Implementing some basic functions, I get the following discrepancy :
> 
> EuclidianDistance1[p_List, q_List] := 
>   Check[With[{m = p - q}, N at Sqrt[m.m]], $Failed]
> 
> EuclidianDistance3 := 
>   Check[Compile[{{p, _Real, 1}, {q, _Real, 1}}, 
>       With[{m = p - q}, Sqrt[m.m]]], $Failed]
> 
> These two functions are ok, and the compiled form about four 
> times faster. 
> The Check prevents obviously inconsistent results to propagate, 
> like in the 
> following situation (two points in different dimensions) :
> 
> EuclidianDistance1[{1., 2., 3.}, {1., 2., 3., 4.}]
> Thread::"tdlen": "Objects of unequal length in \!\(\(\({1.`, 2.`, 
> 3.`}\)\) + \
> \(\({\(\(-1.`\)\), \(\(-2.`\)\), \(\(-3.`\)\), 
> \(\(-4.`\)\)}\)\)\) cannot be \
> combined."
> Out[96]=
> $Failed
> 
> Which is what expected : the return value is $Failed
> 
> Now :
> EuclidianDistance3[{1., 2., 3.}, {1., 2., 3., 4.}]
> 
> CompiledFunction::"cflist": "Non-tensor object generated; 
> proceeding with \
> uncompiled evaluation."
> Thread::"tdlen": "Objects of unequal length in \!\(\(\({1.`, 2.`, 
> 3.`}\)\) + \
> \(\({\(\(-1.`\)\), \(\(-2.`\)\), \(\(-3.`\)\), 
> \(\(-4.`\)\)}\)\)\) cannot be \
> combined."
> 
> \!\(\ at \(\(({1.`, 2.`, 3.`} + {\(-1.`\), \(-2.`\), \(-3.`\), 
> \(-4.`\)})\) . \
> \(({1.`, 2.`, 3.`} + {\(-1.`\), \(-2.`\), \(-3.`\), \(-4.`\)})\)\)\)
> 
> The return value is in this case an unevaluated expression, while 
> $Failed is 
> expected.
> 
> Bug ?
> 
> 


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