Transforms, and DHTML to produce graphs of functions. Enter a
function in terms of x in the top box. Enter minimum and maximum
values for x and y in the next four boxes. Then, hit the Replot!
button. If you make a mistake in entering a formula, use the
Refresh feature of your browser.
atan(x), ceil(x), cos(x), exp(x), floor(x), log(x), max(x,n),
min(x,n), pow(x,n), random(), round(x), sin(x), sqrt(x) and
Once a function is displayed, a Fourier Transform can be
performed by pressing the FFT! button. Although only 512 points
are shown in the upper grapph, a Fast Fourier Transform is
calculated on 1024 points from the entered function. So the
Nyquist frequency for the FT is twice the apparent Nyquist
frequency for the upper plot. Each of the resulting 512 real and
imaginary FT points are squared and added together to produce a
power spectrum. The maximum frequency, ν, and angular freqency,
ω (=2πν), are displayed as determined from the maximum and
mininum x values. The individual data points of the power
spectrum are also listed in the lower text box. The vertical
axis of the Fourier transform can be magnified by changing the
value of Fmax and hitting the lower Replot! button.