SciPy interp1d results are different than MatLab interp1
- by LMO
I'm converting a MatLab program to Python, and I'm having problems understanding why scipy.interpolate.interp1d is giving different results than MatLab interp1.
In MatLab the usage is slightly different:
yi = interp1(x,Y,xi,'cubic')
SciPy:
f = interp1d(x,Y,kind='cubic')
yi = f(xi)
For a trivial example the results are the same:
MatLab:
interp1([0 1 2 3 4], [0 1 2 3 4],[1.5 2.5 3.5],'cubic')
1.5000 2.5000 3.5000
Python:
interp1d([1,2,3,4],[1,2,3,4],kind='cubic')([1.5,2.5,3.5])
array([ 1.5, 2.5, 3.5])
But for a real-world example they are not the same:
x = 0.0000e+000 2.1333e+001 3.2000e+001 1.6000e+004 2.1333e+004 2.3994e+004
Y = -6 -6 20 20 -6 -6
xi = 0.00000 11.72161 23.44322 35.16484... (2048 data points)
Matlab:
-6.0000e+000
-1.2330e+001
-3.7384e+000
...
7.0235e+000
7.0028e+000
6.9821e+000
SciPy:
array([[ -6.00000000e+00],
[ -1.56304101e+01],
[ -2.04908267e+00],
...,
[ 1.64475576e+05],
[ 8.28360759e+04],
[ -5.99999999e+00]])
Any thoughts as to how to can get results that are consistent with MatLab?
