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Contents
module Math
class Stepwise < Function
class Point
attr_reader :x, :y
def initialize(x, y)
@x = x
@y = y
end
end
#
# +:values+
#
# is an array of pairs (+x+, +y+)
#
attr_reader :values
#
# +Math::Stepwise.new(values = [])+
#
# stepwise function
#
# Arguments are:
#
# +values+: an array of (+x+, +y+) pairs
#
#:nodoc:
def initialize(vs = [])
setup(vs)
end
#:doc:
#
# +y(x)+:
#
# Returns a value for any given x
#
#:nodoc:
def y(x)
lookup(x)
end
def label
'stepwise function'
end
class << self
#
# +from_yaml(yaml_hash)+:
#
# creates a Math::Stepwise class from a yaml file which must have the
# relevant fields:
#
# +values+: an array of duples [x, y]
#
def from_yaml(yh)
new(yh['values'])
end
end
private
def lookup(x)
last = nil
self.values.each do
|p|
break if p.x > x
last = p.y
end
last
end
#
# +setup+
#
# setup basically sorts the input array in time creating points
#
#:nodoc:
def setup(vs)
@values = []
sorted = vs.sort { |a, b| a[0] <=> b[0] }
sorted.each { |duple| self.values << Point.new(duple[0], duple[1]) }
#
# keep in mind that vs might be empty
#
@x_start = self.values.first ? self.values.first.x : self.values.first
@x_end = self.values.last ? self.values.last.x : self.values.last
end
end
end
Version data entries
35 entries across 35 versions & 1 rubygems