Hi,
I (well actually a friend) was recently trying to fit a
UnivariateSpline to some data and then evaluate the derivative. The
spline generated fine and could be evaluated (it looked reasonable) but
the derivative would give the error:
File "/usr/lib/pytho
n2.7/dist-packages/scipy/interpolate/fitpack2.py", line 258, in derivatives
raise ValueError("Error code returned by spalde: %s" % ier)
ValueError: Error code returned by spalde: 10
It
turned out that the x-array input was not in ascending order, as the
documentation says is required. The exact data I was using lead to
non-ascending knots.
I recognise this error is not encountered if the
documentation is followed, but the error is uninformative, and it seems
like an easy mistake to make. Especially given the spline still looks
fine otherwise.
In case anyone wants to reproduce the example, the data are:
2.651,1.421
2.581,1.36
2.494,1.256
2.398,1.186
2.328,1.116
2.232,1.046
2.11,0.951
2.041,0.881
1.945,0.837
1.84,0.794
1.727,0.733
1.631,0.689
1.57,0.663
1.483,0.602
1.413,0.567
1.291,0.515
1.203,0.488
1.108,0.445
0.994,0.392
0.898,0.349
0.802,0.314
0.724,0.279
0.619,0.253
0.523,0.218
0.419,0.183
0.314,0.14
0.253,0.096
0.157,0.078
0.087,0.044
Thanks,
Padarn