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Why so slow and not getting faster
*To*: mathgroup at smc.vnet.net
*Subject*: [mg113238] Why so slow and not getting faster
*From*: Sam Takoy <sam.takoy at yahoo.com>
*Date*: Wed, 20 Oct 2010 04:07:21 -0400 (EDT)
Hi,
I ran the following code on two machines (linux and windows) under
identical versions - 7.0.1.0.
On the windows machine, the code takes 10-15 seconds on each run.
On the linux maxhine, the first run took 6 seconds and all subsequent
runs are nearly instantaneous (< 1/10 sec).
1. I accept that my windows machine is slower, but why doesn't it show
similar acceleration in subsequent runs?
2. Even 6 seconds I think is too high. Are these very simple
integrations for Mathematica?
Many thanks in advance,
Sam
FourierCoefficients[f_, order_] := Module[{first, reim},
first = 1/(2 \[Pi]) Integrate[f[a], {a, -\[Pi], \[Pi]}];
Print[first];
reim = Table[(Print[n];
1/\[Pi] Integrate[f[a]*E^(I*n*a), {a, -\[Pi], \[Pi]}]), {n, 1,
order}];
Join[{first}, Map[ComplexExpand[{Re[#], Im[#]}] &, reim]]]
g[a_] := 1/32 (7 - 11 Cos[2 a] - 8 Cos[4 a] - 3 Cos[6 a])
FourierCoefficients[g, 5]
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