[SciPy-User] bug in signal.lsim2
Thu Jan 28 17:00:19 CST 2010
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, <firstname.lastname@example.org> wrote:
> On Thu, Jan 28, 2010 at 3:39 PM, Ryan Krauss <email@example.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 = -------------
>> 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.
> 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.
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