Class: LinearInterpolator

Inherits:
Object
  • Object
show all
Defined in:
lib/linear_interpolator.rb

Overview

This provides basic linear interpolation between any number of arbitrarily defined points. It is used for fuzzy logic. Although, fuzzy logic based on a statistically normal curve provides best results, linear interpolation provides a “gud ‘nuf” approach.

Instance Method Summary collapse

Instance Method Details

#add_point(x, y) ⇒ Object

:nodoc:



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# File 'lib/linear_interpolator.rb', line 5

def add_point(x,y)
  @points ||= []
  @points << [x,y]
  @points = @points.sort_by { |x| x[0] }
end

#value_at(x) ⇒ Object 



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# File 'lib/linear_interpolator.rb', line 10

def value_at(x)
  return 0 if @points.nil?
  return @points[0][1] if x < @points[0][0]
  return @points[-1][1] if x > @points[-1][0]
  
  after,before=nil,nil
  @points.each_with_index do |point,i|
    if(point[0] >= x)
      after = point
      before = @points[i-1]
    end
  end
  
  m=(before[1]-after[1])/(before[0]-after[0]).to_f
  x-=before[0]
  b=before[1]
  
  return m*x+b
end