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# numpy.polynomial.polynomial.polyfromroots

`numpy.polynomial.polynomial.``polyfromroots`(roots)

  Generate a monic polynomial with given roots.

  Return the coefficients of the polynomial

  where the r_n are the roots specified in roots. If a zero has multiplicity n, then it must appear in roots n times. For instance, if 2 is a root of multiplicity three and 3 is a root of multiplicity 2, then roots looks something like [2, 2, 2, 3, 3]. The roots can appear in any order.

  If the returned coefficients are c, then

  The coefficient of the last term is 1 for monic polynomials in this form.

  Parameters : | roots : array_like Sequence containing the roots.
  Returns : | out : ndarray 1-D array of the polynomial’s coefficients If all the roots are real, then out is also real, otherwise it is complex. (see Examples below).

  See also

  `chebfromroots`, `legfromroots`, `lagfromroots`, `hermfromroots`, `hermefromroots`

  Notes

  The coefficients are determined by multiplying together linear factors of the form (x - r_i), i.e.

  where `n == len(roots) - 1`; note that this implies that 1 is always returned for .

  Examples

      >>> import numpy.polynomial as P
      >>> P.polyfromroots((-1,0,1)) # x(x - 1)(x + 1) = x^3 - x
      array([ 0., -1.,  0.,  1.])
      >>> j = complex(0,1)
      >>> P.polyfromroots((-j,j)) # complex returned, though values are real
      array([ 1.+0.j,  0.+0.j,  1.+0.j])

### Navigation

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- NumPy v1.7 Manual (DRAFT) »
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