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# scipy.special.ellipkm1

`scipy.special.``ellipkm1`(p) = <ufunc 'ellipkm1'>

  Complete elliptic integral of the first kind around m = 1

  This function is defined as

  \[K(p) = \int_0^{\pi/2} [1 - m \sin(t)^2]^{-1/2} dt\]

  where m = 1 - p.

  Parameters: | p : array_like Defines the parameter of the elliptic integral as m = 1 - p.
  Returns: | K : ndarray Value of the elliptic integral.

  See also

  `ellipk`
    Complete elliptic integral of the first kind
  `ellipkinc`
    Incomplete elliptic integral of the first kind
  `ellipe`
    Complete elliptic integral of the second kind
  `ellipeinc`
    Incomplete elliptic integral of the second kind

  Notes

  Wrapper for the Cephes [R406] routine ellpk.

  For p <= 1, computation uses the approximation,

  \[K(p) \approx P(p) - \log(p) Q(p),\]

  where \(P\) and \(Q\) are tenth-order polynomials. The argument p is used internally rather than m so that the logarithmic singularity at m = 1 will be shifted to the origin; this preserves maximum accuracy. For p > 1, the identity

  \[K(p) = K(1/p)/\sqrt(p)\]

  is used.

  References

  [R406] | (1, 2) Cephes Mathematical Functions Library, http://www.netlib.org/cephes/index.html