# Contents of response\_\*.txt

**URL:** <https://community.mrtrix.org/t/contents-of-response-txt/1918>\
**Category:** Uncategorized\
**Created:** [September 18, 2018, 9:29pm UTC](https://community.mrtrix.org/t/contents-of-response-txt/1918 "2018-09-18T21:29:21Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![zeydabadi](https://community.mrtrix.org/user_avatar/community.mrtrix.org/zeydabadi/32/1425_2.png) [@zeydabadi](https://community.mrtrix.org/u/zeydabadi)\
**Post date:** [September 18, 2018, 9:29pm UTC](https://community.mrtrix.org/t/contents-of-response-txt/1918/1 "2018-09-18T21:29:22Z")

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Hello all,

I was hoping to find a description of the format and contents of response\_\*.txt files [here](https://mrtrix.readthedocs.io/en/0.3.16/reference/scripts/dwi2response.html?highlight=dwi2response) but couldn’t find it.  
I appreciate any clarification.

Thank you,  
Mahmoud

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**Author:** ![jdtournier](https://community.mrtrix.org/user_avatar/community.mrtrix.org/jdtournier/32/2594_2.png) [@jdtournier](https://community.mrtrix.org/u/jdtournier)\
**Post date:** [September 18, 2018, 10:16pm UTC](https://community.mrtrix.org/t/contents-of-response-txt/1918/2 "2018-09-18T22:16:44Z")

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A better place to look would be [here](https://mrtrix.readthedocs.io/en/latest/constrained_spherical_deconvolution/response_function_estimation.html) – but even then, I note the description is pretty vague… We should definitely fix that.

Thankfully, it’s a pretty simple format. Each row corresponds to a different shell (in order of increasing _b_-value), and for each row, the values correspond to the even, _m_=0 (axially symmetric) SH coefficients of the expected DW signal, starting from _l_=0, _l_=2, …, l=10 (by default). That’s pretty much all there is to it…

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**Author:** ![ThijsDhollander](https://community.mrtrix.org/user_avatar/community.mrtrix.org/thijsdhollander/32/1617_2.png) [@ThijsDhollander](https://community.mrtrix.org/u/ThijsDhollander)\
**Post date:** [September 19, 2018, 6:10am UTC](https://community.mrtrix.org/t/contents-of-response-txt/1918/3 "2018-09-19T06:10:18Z")

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Hi Mahmoud,

See also my reply in [-nan in response\_wm.txt](https://community.mrtrix.org/t/nan-in-response-wm-txt/1767/6) : @jdtournier’s answer here should help you understand why the first line in the WM response would have those zeros.

Cheers,  
Thijs