def draw_fft(self):
if len(self.points) < 1:
return
pts = map(lambda p: p[1] - self.offset, self.points)
out = numpy.fft.rfft(pts)
c = len(out)
norm = 0
for i in range(c/2):
norm += numpy.real(out[i])**2 + numpy.imag(out[i])**2
norm = math.sqrt(norm)
if norm <= 0:
return
for i in range(1, SignalKPlot.NUM_X_DIV):
x = float(i) / SignalKPlot.NUM_X_DIV
glRasterPos2d(x, .95)
period = 3/math.exp(x) # incorrect!!
SignalKPlot.drawputs(str(period))
glPushMatrix()
glBegin(GL_LINE_STRIP)
for i in range(c/2):
glVertex2d(float(i) * 2 / (c-2), abs(out[i]) / norm)
glEnd()
glPopMatrix()
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