[SciPy-Dev] maybe a bug into scipy.interpolate.Rbf?

Luca Penasa luca.penasa@gmail....
Tue May 17 10:12:07 CDT 2011

scipy version 0.9.0-r1

I am trying to use scipy.interpolate.Rbf to interpolate a
multidimensional function.

I see the Rbf class permits to use a callable function as radial basis
function, but gives me an error, see below:

My self defined rbf:

def ElasticDeformationRBF(this, r): 
	ratio = ((r**2) / this.epsilon)
	out = ratio * np.log(ratio) + 1 - ratio
	return out

interpolator = scipy.interpolate.Rbf(somex, somey,

The error is:

 /usr/lib64/python2.6/site-packages/scipy/interpolate/rbf.pyc in
__init__(self, *args, **kwargs)
    195             setattr(self, item, value)
--> 197         self.A = self._init_function(r) -
    198         self.nodes = linalg.solve(self.A, self.di)

/usr/lib64/python2.6/site-packages/scipy/interpolate/rbf.pyc in
_init_function(self, r)
    159                 self._function = self.function
    160             elif argcount == 2:
--> 161                 if sys.version_info[0] >= 3:
    162                     self._function = function.__get__(self, Rbf)
    163                 else:

NameError: global name 'sys' is not defined

Maybe a missing import sys??

test_function_is_callable() from rbf's tests does not give any error.

help docs say, about callable function:

"If callable, then it must take 2 arguments (self, r).  The epsilon
        parameter will be available as self.epsilon."

So i cannot understand if it is my fault.
Any idea?

Thank you

Luca Penasa
Student at Geosciences Dpt.
University of Padua (IT)

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