<p dir="auto">In python2.6.6 (I do not have more recent versions available at work) there is a problem with scipy.special.gammaincinv  with the second parameter (the quantile) set as 0.25.  For example</p>
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<blockquote>
<p dir="auto">gammaincinv(1.0, 0.25)<br>
0.0<br>
gammaincinv(2.0, 0.25)<br>
0.0<br>
gammaincinv(3.0, 0.25)<br>
0.0<br>
gammaincinv(3.0, 0.24)<br>
1.6894710461335511<br>
gammaincinv(1.0, 0.24)<br>
0.27443684570176036<br>
gammaincinv(1.0, 0.26)<br>
0.30110509278392172</p>
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</blockquote>
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<p dir="auto"><em>Original ticket <a href="http://projects.scipy.org/scipy/ticket/975" rel="nofollow">http://projects.scipy.org/scipy/ticket/975</a> on 2009-07-15 by <a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/pierregm/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://github.com/pierregm">@pierregm</a>, assigned to <a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/pv/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://github.com/pv">@pv</a>.</em></p>
<p dir="auto">special.gammaincinv(x,y) fails when y=0.25 for any value of x.</p>
<p dir="auto">Could it be a problem in c_misc/gammaincinv.c ?<br>
(<a href="http://article.gmane.org/gmane.comp.python.scientific.devel/11271" rel="nofollow">http://article.gmane.org/gmane.comp.python.scientific.devel/11271</a>)</p>