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# scipy.fft.fhtoffset

scipy.fft.fhtoffset(dln, mu, initial=0.0, bias=0.0)

  Return optimal offset for a fast Hankel transform.

  Returns an offset close to initial that fulfils the low-ringing condition of [1] for the fast Hankel transform `fht` with logarithmic spacing dln, order mu and bias bias.

  Parameters:
    dln float

      Uniform logarithmic spacing of the transform.

    mu float

      Order of the Hankel transform, any positive or negative real number.

    initial float, optional

      Initial value for the offset. Returns the closest value that fulfils the low-ringing condition.

    bias float, optional

      Exponent of power law bias, any positive or negative real number.

  Returns:
    offset float

      Optimal offset of the uniform logarithmic spacing of the transform that fulfils a low-ringing condition.

  See also

  `fht`

    Definition of the fast Hankel transform.

  References

  [1]

  Hamilton A. J. S., 2000, MNRAS, 312, 257 (astro-ph/9905191)

  Examples

      >>> from scipy.fft import fhtoffset
      >>> dln = 0.1
      >>> mu = 2.0
      >>> initial = 0.5
      >>> bias = 0.0
      >>> offset = fhtoffset(dln, mu, initial, bias)
      >>> offset
      0.5454581477676637