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Real valued input

if h(n) is real, as in most speech processing, tex2html_wrap_inline2889 is symmetric. Most useful.

Similarly, if h(n) is even, i.e. h(n) = h(-n) then tex2html_wrap_inline2889 is real.

Fourier transforms of real valued data can be done roughly twice as fast (only half the complex numbers are present) - look for realft in Numerical recipes.

Speech Vision Robotics group/Tony Robinson