<p dir="auto">I've been checking values in Scipy's implementation of hyp1f1 against other implementations and I noticed some discrepancies where Scipy's solution seems to be off.</p>
<p dir="auto">scipy.special.hyp1f1(a,b,c) vs M(a,b,c) from (<a href="http://keisan.casio.com/exec/system/1349143651" rel="nofollow">http://keisan.casio.com/exec/system/1349143651</a>).</p>
<p dir="auto">In particular, take small values of a, b, and c, say a = 1, b = 5, and c = 0.01.</p>
<p dir="auto">Both equal: 1.002003338101197 (with differences in the remaining digits)</p>
<p dir="auto">However change a to 50 and b to 100. a = 50, b = 100, and c = 0.01.</p>
<p dir="auto">scipy.special.hyp1f1(a,b,c) = 1774259915037.1118<br>
M(a,b,c) = 1.005012645242146341004</p>
<p dir="auto">I've double checked on Matlab and the latter is correct. In general, higher values of a and b give the scipy implementation greater trouble. This is using scipy version 0.13.3.  There was an earlier report similar in nature (<a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="13649106" data-permission-text="Title is private" data-url="https://github.com/scipy/scipy/issues/946" data-hovercard-type="issue" data-hovercard-url="/scipy/scipy/issues/946/hovercard" href="https://github.com/scipy/scipy/issues/946">#946</a>) which has since been closed.</p>
<p dir="auto">Mathematica gives 0.999737 for the following, but in scipy we get -1.87e8:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="In [22]: scipy.special.hyp1f1(0.01, 150, -4)
Out[22]: -187159708.75814998

In [23]: scipy.__version__ 
Out[23]: '0.14.0b1'"><pre class="notranslate"><code class="notranslate">In [22]: scipy.special.hyp1f1(0.01, 150, -4)
Out[22]: -187159708.75814998

In [23]: scipy.__version__ 
Out[23]: '0.14.0b1'
</code></pre></div>