Hello,
You will find a description of the actual problem which is solved by the
generated code : http://arxiv.org/pdf/1206.5072v1.pdf
See particularly page 6, where I explain the way the code generation
works. However, be warned that the code snipplets are quite obsolete,
since the generated code is now more efficient.
For matrices M_k(v) (the ones the thread is about), Antoine's answer
give a solution because the element of this matrix are linear
combinations of the v(i)'s.
But for other matrices, wich are derivatives of the fonctions expressing
the non-linear system with respect to state or parameters, the terms to
assemble are non-linear algebraic expressions mixing states and v(i)'s.
S.
Le 24/04/2015 15:19, Brian Bouterse a écrit :
I don't know much about scilab optimizations, but trying to
hand-optimize auto-generated code almost certainly will result in
correctness problems. It's likely better to make your improvements in
the software that is generating the scilab code. I think the main
feature there is to have it generate a vectorized implementation
instead of a procedural one (as you have now).
-Brian
On Fri, Apr 24, 2015 at 8:34 AM, Stéphane Mottelet
<[email protected] <mailto:[email protected]>> wrote:
Hello,
this is not trivial indexing, in fact some terms are linear
combination of v's components
M1_v=[v(17)
v(104)
v(149)
-(v(18)+v(63)+v(103))
-(v(18)+v(63)+v(103))
v(17)
...
v(104)
v(149)
]
How do you take this into account in your proposed method ? These
combinations are sums of influxes in a metabolic network, and the
code is automatically generated.
S.
Le 24/04/2015 13:48, Samuel Gougeon a écrit :
Le 24/04/2015 13:36, Samuel Gougeon a écrit :
Hello Stephane,
You can speed up by a factor larger than 100 just by calling v
once (or 3 times) instead of ~1000, as shown by this test:
Actually, to be more accurate, the right comparative test is the
following:
function test2()
v = rand(172,1);
p = grand(1,839,"unf",1,173)
// Part 1: 1 call to v()
tic()
for i=1:1000
m1_v = v(p)
end
disp(toc())
// Part 2 : 839 calls to v()
deff("test3()", "for i=1:1000, M1_v = ["+strcat("v("+string(p)+")")+"],
end")
tic()
test3()
disp(toc())
endfunction
In this version, the compilation time used by execstr() is no
longer taken into account.
The results are still explicit:
-->test2()
0.016
0.78
So, a speed-up by ~x 50
Samuel
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Brian Bouterse
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