extrapolation in ufun throwed errors

[miroslavfikar]

I came across situation when interpolation of u in ufun was requested beyond the actual time interval. Attached MWE file throws error, proposed modification resolves the issue. There were two possibilities to resolve the issue: either to take the highest value of time known (interpolation) or to prolonge the last interval to the right (extrapolation). I chose the first one to be consistent with already treated case to the left.

testh2.txt

[murrayrm]

@miroslavfikar It would be great to add a unit test the triggers the error (prior to your fix).

[coveralls]

Coverage decreased (-0.002%) to 92.721% when pulling 9bd61b0 on miroslavfikar:mifi_ufun into 2ce4bbd on python-control:master.

[murrayrm]

I updated the fix to use extrapolation, since this is what is supposed to happen. The example now runs without throwing and error. (I couldn't figure out how to create a simple unit test since it seem to depend on the integrator asking to sample outside of the time range.)

@miroslavfikar It would be useful if you can confirm that the new version gives a correct result for your example.

[miroslavfikar]

@murrayrm Yes, I confirm, I get the correct results with your commit, thanks.