<div dir="ltr"><div>Hi Arnold,</div><div><br></div><div>This is just warning you that in some voxel/voxel's the fwDTI's non-linear convergence procedure did not reach the global minimum with the default number of iteration defined in scipy.optimize.leastsq. For faster convergence try using fwDTI's Jacobian by calling the fwDTI model in the following way:</div><div><br></div><div><span style="font-size:12.8px">fwdtimodel = fwdti.FreeWaterTensorModel(</span><wbr style="font-size:12.8px"><span style="font-size:12.8px">grab, fit_method="NLS", jac=True)</span><br></div><div><span style="font-size:12.8px"><br></span></div><div><span style="font-size:12.8px">This warning is typically generated by background voxels. I also recommend you to mask your data when fitting.</span></div><div><span style="font-size:12.8px"><br></span></div><div><span style="font-size:12.8px">Best,</span></div><div><span style="font-size:12.8px">Rafael Henriques</span></div><div><span style="font-size:12.8px"><br></span></div><br><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br>
Date: Thu, 28 Dec 2017 22:11:21 -0600<br>
From: Arnold Evia <<a href="mailto:ajevia@gmail.com">ajevia@gmail.com</a>><br>
To: <a href="mailto:neuroimaging@python.org">neuroimaging@python.org</a><br>
Subject: [Neuroimaging] [Dipy] Warnings when running free water model<br>
Message-ID:<br>
        <<a href="mailto:CALqRRQRjHaUqTF16Ayphhq%2BVrBT25jT5iUZ1M4tZE3R1LENTPQ@mail.gmail.com">CALqRRQRjHaUqTF16Ayphhq+<wbr>VrBT25jT5iUZ1M4tZE3R1LENTPQ@<wbr>mail.gmail.com</a>><br>
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<br>
Hello,<br>
<br>
I am applying the free water dti model to my data, and receive the<br>
following warnings:<br>
<br>
/Users/arnoldevia/anaconda3/<wbr>lib/python3.6/site-packages/<wbr>scipy/optimize/minpack.py:427:<br>
RuntimeWarning: Number of calls to function has reached maxfev = 1800.<br>
  warnings.warn(errors[info][0], RuntimeWarning)<br>
<br>
/Users/arnoldevia/personal_<wbr>programs/dipy/dipy/reconst/<wbr>fwdti.py:454:<br>
RuntimeWarning: overflow encountered in exp<br>
  y = (1-f) * np.exp(np.dot(design_matrix, tensor[:7])) + \<br>
<br>
The code I am using is essentially the same as the code used in the free<br>
water model documentation.<br>
What do these warnings mean, and what should I do to address them?<br>
Please let me know if additional information is needed.<br>
<br>
Thanks in advance!<br>
-Arnold Evia<br>
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