-------- Original Message --------

Subject: [OctDev] slow structs

Date: Wed, 17 Dec 2008 18:13:17 -0600

From: Jonathan Kotta <

[hidden email]>

To:

[hidden email]
I have a problem where a vector within a struct is much slower to

index than a plain vector (~8x slower) .

x = zeros(1e6,1);

s.x = x;

subset = 500e3:600e3-1;

y = randn(length(subset),1);

for i = 1:5

tic; x(subset) = y; toc;

end

for i = 1:5

tic; s.x(subset) = y; toc;

end

tic;

for i = 1:100

x(subset) = y;

end

toc;

tic;

for i = 1:100

s.x(subset) = y;

end

toc;

Tested using Octave 3.0.3 on x86-64.

--

Thanks,

Jonathan Kotta

Hofstadter's Law:

It always takes longer than you expect, even

when you take into account Hofstadter's Law.

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