Reply by July 31, 20092009-07-31
For starters apologies in advance if I'm in in the wrong NG.

Downloaded fftw and I'm trying to get an assessment on the output
surround the command 'bench -sib246'.

On my machine this outputs:

C:\dev\vc++_2008\fft\fftw>lib /def:libfftw3-3.def
'lib' is not recognized as an internal or external command,
operable program or batch file.

C:\dev\vc++_2008\fft\fftw>bench -s
option -s requires an argument

C:\dev\vc++_2008\fft\fftw>bench -sib256
Problem: ib256, setup: 46.36 ms, time: 2.64 us, ``mflops'': 3881

Three questions:

a) I'm not following what the 46.36ms of 'setup' entails and the di
b) How is time measured here.  Is this as simple as:

  //start the clock
  start = std::clock();
  // stop the clock
  elapsed = (diff_type)std::clock() - start;
  elapsed /= CLOCKS_PER_SEC;

c) bench executed "in-place backward complex transform of size 256".
This in my view means an array length 256 of complex type.  I suspect
the content is irrelevant?  Just trying to get a feel for the 'what
the complex type entails'