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Diffstat (limited to 'numpy/polynomial/laguerre.py')
| -rw-r--r-- | numpy/polynomial/laguerre.py | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/numpy/polynomial/laguerre.py b/numpy/polynomial/laguerre.py index fc9afec00..866aab5c4 100644 --- a/numpy/polynomial/laguerre.py +++ b/numpy/polynomial/laguerre.py @@ -283,10 +283,17 @@ def lagfromroots(roots) : return np.ones(1) else : [roots] = pu.as_series([roots], trim=False) - prd = np.array([1], dtype=roots.dtype) - for r in roots: - prd = lagsub(lagmulx(prd), r*prd) - return prd + roots.sort() + n = len(roots) + p = [lagline(-r, 1) for r in roots] + while n > 1: + m = n//2 + tmp = [lagmul(p[i], p[i+m]) for i in range(m)] + if n%2: + tmp[0] = lagmul(tmp[0], p[-1]) + p = tmp + n = m + return p[0] def lagadd(c1, c2): |