[Neuroimaging] failure using DIPY Free Water Elimination DTI

[Ping-Hong Yeh]

Hi Ariel,

 Have you got the chance to look at the DWI data that was attached to the
previous email?

Thank you for your time.

Ping

On Sat, Dec 29, 2018 at 1:12 AM Ariel Rokem <arokem at gmail.com> wrote:

> Hi Ping,
>
> Thanks for your email. Hard to say exactly what is going on without
> further information. Could you tell us more about the data you are using?
> How many b-values? How many directions? Any chance you could share the data
> from the voxel that caused that error to be raised?
>
> Thanks!
>
> Ariel
>
> On Thu, Dec 27, 2018 at 6:55 AM Ping-Hong Yeh <pinghongyeh at gmail.com>
> wrote:
>
>> Hi Dipy Users,
>>
>>  I've ran into errors "Eigenvalues did not  converge" when using the free
>> water elimination model,
>> and here is the error message:
>>
>>   File
>> "/Users/yehp/anaconda3/lib/python3.6/site-packages/dipy/reconst/dti.py",
>> line 1615, in _decompose_tensor_nan
>>     min_diffusivity=min_diffusivity)
>>   File
>> "/Users/yehp/anaconda3/lib/python3.6/site-packages/dipy/reconst/dti.py",
>> line 1946, in decompose_tensor
>>     eigenvals, eigenvecs = eigh(tensor)
>>   File
>> "/Users/yehp/anaconda3/lib/python3.6/site-packages/dipy/utils/arrfuncs.py",
>> line 128, in eigh
>>     return np.linalg.eigh(a, UPLO)
>>   File
>> "/Users/yehp/anaconda3/lib/python3.6/site-packages/numpy/linalg/linalg.py",
>> line 1291, in eigh
>>     w, vt = gufunc(a, signature=signature, extobj=extobj)
>>   File
>> "/Users/yehp/anaconda3/lib/python3.6/site-packages/numpy/linalg/linalg.py",
>> line 95, in _raise_linalgerror_eigenvalues_nonconvergence
>>     raise LinAlgError("Eigenvalues did not converge")
>> numpy.linalg.linalg.LinAlgError: Eigenvalues did not converge
>>
>>
>> Any suggestions?
>>
>> Thank you.
>>
>> Ping
>>
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