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\ stepfft.4th
\
\ Compute the FFT of a square pulse.
\
\ Requires:
\
\ matrix.4th
\ fft.4th
\
include matrix
include fft
2048 1 fmatrix pulse
variable pulse_width
100 pulse_width !
fvariable pulse_height
1e pulse_height f!
." Initial pulse width is " pulse_width @ . cr
variable start_pulse
variable stop_pulse
: gen_pulse ( -- | generate the pulse profile )
pulse mat_size@ drop 2/
dup pulse_width @ - start_pulse !
pulse_width @ + stop_pulse !
pulse mat_size@ drop 1+ 1 do
i start_pulse @ >
if
i stop_pulse @ < if
pulse_height f@ i 1 pulse fmat!
else
0e i 1 pulse fmat!
then
else
0e i 1 pulse fmat!
then
0e i 1+ 1 pulse fmat! \ imaginary component of the pulse
2 +loop ;
: go ( -- compute the FFT and display real and imaginary components and power )
gen_pulse
pulse fft
pulse mat_size@ drop 1+ 1 do
i 4 .r 2 spaces
i 1 pulse fmat@ fdup fdup f. f* 2 spaces
i 1+ 1 pulse fmat@ fdup fdup f. f* f+ 2 spaces
f. cr
2 +loop ;
." Type 'go' to generate the FFT and print it." cr
|
