fft: reducing size of dotprod objects for faster processing
fft: reducing size of dotprod objects for faster processing

  * first twiddle is exp(0)=1
  * no multiplication necessary for first value
  * need method to compute DC value quickly

jgaeddert/liquid-dsp,JayKickliter/liquid-dsp,biotrump/liquid-dsp,jgaeddert/liquid-dsp,cjcliffe/liquid-dsp,wangning223/liquid-dsp,JayKickliter/liquid-dsp,biotrump/liquid-dsp,JayKickliter/liquid-dsp,manuts/liquid-dsp,wangning223/liquid-dsp,cjcliffe/liquid-dsp,cjcliffe/liquid-dsp,jgaeddert/liquid-dsp,wangning223/liquid-dsp,andrepuschmann/liquid-dsp,manuts/liquid-dsp,andrepuschmann/liquid-dsp,jgaeddert/liquid-dsp,cjcliffe/liquid-dsp,manuts/liquid-dsp,cjcliffe/liquid-dsp,andrepuschmann/liquid-dsp,JayKickliter/liquid-dsp,wangning223/liquid-dsp,biotrump/liquid-dsp,andrepuschmann/liquid-dsp,jgaeddert/liquid-dsp,biotrump/liquid-dsp,biotrump/liquid-dsp,wangning223/liquid-dsp,JayKickliter/liquid-dsp,andrepuschmann/liquid-dsp,manuts/liquid-dsp,manuts/liquid-dsp