# this demos forward and inverse fft.  Note the xtags are incorrect.
tt= linspace( 0, 10*TAU, 1024 )
ff= 2*sin( tt )
plot( 0, ff )
f= fft( ff )
plot( 1, f )
ff2= ifft( f )
plot( 2, ff2 )
ff3= fft( ff2 )
plot( 3, ff3 )
writeToPng('demoFFT.png')