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Incorrect roots found #8
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I cannot reproduce the issue. This is the result I get:
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I did few other tests, accuracy varies greatly depending on parameters (tolerances, number of shifts, etc.). What parameters do you use? What are residuals for each root? I use defaults (Intel C++ on Windows). I work with reciprocal polynomials with integer coefficients, most of them have ill-conditioned roots (especially cyclotomic polys). So far I was not able to get consistent accuracy with RpolyPlusPlus (one set of parameters work for one polynomial but not for the other). I compare it with DHSEQR from MKL/LAPACK, which is very stable (but slow). One more thing, it is more numerically robust to use |
I used the default parameters. Did you enable any particular optimization flags when compiling using Intel C++? |
I have been testing the library on some polynomials with integer coefficients. On many of them incorrect roots are found. One of the examples:
Coefficients: [1,0,-1,0,1,1,1,1,1,1,1,0,-1,0,1]
Roots found:
True roots:
Roots are sorted by magnitude.
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