# st: mata polyroots issue

 From John Bates To Stata Subject st: mata polyroots issue Date Fri, 8 May 2009 06:24:45 -0700 (PDT)

```<>
Hi,

I am running Stata 10.1 on Mac OS 10.4.  The following issue is perplexing me:

-------
mata:
mata clear
polynomial1 = (1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,-30,29)
polyeval(polynomial1,1)
polyroots(polynomial1)
-------

The
polyeval line makes it clear that x=1 is a root for this polynomial.
However, 1 is not a reported result for polyroots.  What is odd is that
if I add or subtract a zero term to the polynomial, polyroots() will
then correctly report x=1 as a root.  i.e., the following works:

-------
mata:
mata clear
polynomial1 = (1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,-30,29)
polynomial2 = (1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,-30,29)
polynomial3 = (1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,-30,29)
polyroots(polynomial2)
polyroots(polynomial3)
-------

Does anybody know what is going on here?

Lirac

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