Hmmm. Thanks. That solves the immediate problem. I am letting my students choose between Matlab and Python for projects in my course. This one my erode their confidence in Python/Scipy a bit. On Thu, Jan 28, 2010 at 3:05 PM, <josef.pktd@gmail.com> wrote:
On Thu, Jan 28, 2010 at 3:39 PM, Ryan Krauss <ryanlists@gmail.com> wrote:
I believe I have discovered a bug in signal.lsim2. I believe the short attached script illustrates the problem. I was trying to predict the response of a transfer function with a pure integrator:
g G = ------------- s(s+p)
to a finite width pulse. lsim2 seems to handle the step response just fine, but says that the pulse response is exactly 0.0 for the entire time of the simulation. Obviously, this isn't the right answer.
I am running scipy 0.7.0 and numpy 1.2.1 on Ubuntu 9.04, but I also have the same problem on Windows running 0.7.1 and 1.4.0.
Thanks,
Ryan
When I add a small noise
u2 = zeros(N) + 1e-14
or for u2[:50] = amp
or for u2[50:200] = amp
it seems to work.
This might be a tricky bug.
Josef
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