RE: LuaJIT Matrix Algebra Function

  • From: "Beddell, Thomas Edmund" <ThomasEdmund.Beddell@xxxxxxxxx>
  • To: "luajit@xxxxxxxxxxxxx" <luajit@xxxxxxxxxxxxx>
  • Date: Thu, 7 Aug 2014 20:11:17 +0000

Hi Alex,

I tried it and it says “cannot resolve symbol malloc. The specified procedure 
cannot be found”. Do I have to declare it on C side?

Best regards,

Thomas Beddell

From: luajit-bounce@xxxxxxxxxxxxx [mailto:luajit-bounce@xxxxxxxxxxxxx] On 
Behalf Of Alex
Sent: 7. august 2014 21:49
To: luajit@xxxxxxxxxxxxx
Subject: Re: LuaJIT Matrix Algebra Function

Here's a fully-compileable FFI version, based off of Kordic's:

https://gist.github.com/ColonelThirtyTwo/56a06902c49f57edd70d<https://urldefense.proofpoint.com/v1/url?u=https://gist.github.com/ColonelThirtyTwo/56a06902c49f57edd70d&k=rYVT%2BQIbByDGfw04ADASxQ%3D%3D%0A&r=Z%2BQTzSXoYfn2aVXXze9h9xUjv%2BDjFRaIHobDQaXRmqQ%3D%0A&m=xC9egAR1WrU%2BIwktLIE9oPbTsIQIdQHT7%2B43FA8Gj5M%3D%0A&s=854392d4bf40bd86d842231145399494de1fd032d73ec84af8599f7081e89e54>

It runs much faster. Primarily, large allocations (>128 bytes) aren't jit 
compiled [1]. Calls to malloc are though, so this code allocates the matrices 
with that. Additionally, caching the `entries` field in a local actually hurts 
performance [2].

[1] 
http://luajit.org/ext_ffi_semantics.html<https://urldefense.proofpoint.com/v1/url?u=http://luajit.org/ext_ffi_semantics.html&k=rYVT%2BQIbByDGfw04ADASxQ%3D%3D%0A&r=Z%2BQTzSXoYfn2aVXXze9h9xUjv%2BDjFRaIHobDQaXRmqQ%3D%0A&m=xC9egAR1WrU%2BIwktLIE9oPbTsIQIdQHT7%2B43FA8Gj5M%3D%0A&s=ccf464722827355dcd96f18d60f2fb9e839a9fa2ff9642c6e7a7325ed4d47356>
 in the Current Status section
[2] 
http://wiki.luajit.org/Numerical-Computing-Performance-Guide<https://urldefense.proofpoint.com/v1/url?u=http://wiki.luajit.org/Numerical-Computing-Performance-Guide&k=rYVT%2BQIbByDGfw04ADASxQ%3D%3D%0A&r=Z%2BQTzSXoYfn2aVXXze9h9xUjv%2BDjFRaIHobDQaXRmqQ%3D%0A&m=xC9egAR1WrU%2BIwktLIE9oPbTsIQIdQHT7%2B43FA8Gj5M%3D%0A&s=a714796abfb857b1a87d509d9ebc0eabc196c88208f1f478213a17173d95a9f1>,
 confirmed with my tests.

--
Sincerely,
Alex Parrill

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