Module: IERS::Interpolation Private

Defined in:
lib/iers/interpolation.rb

This module is part of a private API. You should avoid using this module if possible, as it may be removed or be changed in the future.

Class Method Summary collapse

Class Method Details

.lagrange(xs, ys, x) ⇒ Float

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Parameters:

  • xs (Array<Float>) —

    x-coordinates

  • ys (Array<Float>) —

    y-coordinates

  • x (Float) —

    interpolation point

Returns:

  • (Float) 


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# File 'lib/iers/interpolation.rb', line 27

def lagrange(xs, ys, x)
  n = xs.size

  unless n == ys.size
    raise ArgumentError, "xs and ys must have the same size"
  end

  unless n >= 2
    raise ArgumentError, "lagrange interpolation requires at least 2 points"
  end

  result = 0.0
  n.times do |i|
    basis = 1.0
    n.times do |j|
      next if i == j
      basis *= (x - xs[j]) / (xs[i] - xs[j])
    end
    result += ys[i] * basis
  end
  result
end

.linear(xs, ys, x) ⇒ Float

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Parameters:

  • xs (Array<Float>) —

    x-coordinates (exactly 2)

  • ys (Array<Float>) —

    y-coordinates (exactly 2)

  • x (Float) —

    interpolation point

Returns:

  • (Float) 


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# File 'lib/iers/interpolation.rb', line 12

def linear(xs, ys, x)
  unless xs.size == 2 && ys.size == 2
    raise ArgumentError, "linear interpolation requires exactly 2 points"
  end

  x0, x1 = xs
  y0, y1 = ys
  t = (x - x0) / (x1 - x0)
  y0 + t * (y1 - y0)
end