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Re: Looking to time how long a command takes in mathematica 6 tia

  • To: mathgroup at smc.vnet.net
  • Subject: [mg97070] Re: Looking to time how long a command takes in mathematica 6 tia
  • From: Alexei Boulbitch <Alexei.Boulbitch at iee.lu>
  • Date: Wed, 4 Mar 2009 07:14:08 -0500 (EST)

Hi, Aloha ,
I think, you should write "<= ", rather than "=" in the definition of 
your piecewise function. Have a look at this:

In[16]:= f[x_] :=
 Piecewise[{{4.*x^2 - 4.*x, 0 <= x <= 1}, {-2*x^2 + 8*x - 6,
    1 <= x <= 3}, {x^2 - 10*x + 21,
    3 <= x <= 7}, {-1/2*x^2 + 11*x - 105/2,
    7 <= x <= 15}, {.5714285714*x^2 - 21.14285714*x + 188.5714286,
    15 <= x <= 22}, {-.8*x^2 + 39.2*x - 475.2, 22 <= x <= 27}}]

In[20]:= Timing[Play[f[x], {x, 0, 27}]]

Out[20]= {0.031, (Sound[
 SampledSoundFunction[
  CompiledFunction[{Blank[Integer]}, {{2, 0, 0}, {3, 0, 1}}, {0, 1, 3,
     0, 0}, {{1, 5}, {8, 0., 0}, {8, 0.000125, 1}, {15, 1, 0, 2}, {21,
      1, 2, 1}, {18, 0, 1, 0}, {
     54, Function[{
       Play`Time5}, $CellContext`f[$CellContext`x]], {$CellContext`x,
       3, 0, 0, Block}, 2, 0, 0, 3, 0, 1}, {
     8, -0.5000937551520472, 2}, {18, 1, 2, 1}, {
     8, 0.13333620140328437`, 2}, {21, 1, 2, 1}, {2}},
    Function[{Play`Time5},
     Block[{$CellContext`x = 0. + 0.000125 Play`Time5}, \
($CellContext`f[$CellContext`x] - 0.5000937551520472)
        0.13333620140328437`]], Evaluate], 216000, 8000]])}

Have a success, Alexei




Grettings All

I'm running this command
Play[Piecewise[{{4.000000000*x^2 - 4.000000000*x,
    0 = x <= 1}, {-2*x^2 + 8*x - 6, 1 = x <= 3}, {x^2 - 10*x + 21,
    3 = x <= 7}, {-1/2*x^2 + 11*x - 105/2,
    7 = x <= 15}, {.5714285714*x^2 - 21.14285714*x + 188.5714286,
    15 = x <= 22}, {-.8000000000*x^2 + 39.20000000*x - 475.2000000,
    22 = x <= 27}}], {x, 0, 27}]

and it's taking extremely long and would like to find out how long it
takes to run this line.  Also if anyone has a more efficient way of
using this command please let me know.  I'm just trying to output the
wave file to an audio file.

Aloha
sal2


-- 
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