Class: Gecode::Constraints::Int::Arithmetic::SquaredExpressionStub

Inherits:
CompositeStub show all
Defined in:
lib/gecoder/interface/constraints/int/arithmetic.rb

Overview

Describes a CompositeStub for the squared constraint, which constrain the squared value of the variable.

Examples

# The value of +x*x+ must be equal to y.
x.squared.must == y

# The value of +x*x+ must be less than or equal to 16, with +bool+ as 
# reification variable and +domain+ as strength.
x.squared.must_be.less_or_equal(16, :reify => bool, :strength => :domain)

Instance Method Summary collapse

Methods inherited from CompositeStub

#initialize

Methods inherited from CompositeStub

#initialize

Methods included from LeftHandSideMethods

#must, #must_not

Methods inherited from ExpressionStub

#initialize

Constructor Details

This class inherits a constructor from Gecode::Constraints::Int::CompositeStub

Instance Method Details

#constrain_equal(variable, params, constrain) ⇒ Object 



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# File 'lib/gecoder/interface/constraints/int/arithmetic.rb', line 99

def constrain_equal(variable, params, constrain)
  lhs = @params[:lhs]
  if constrain
    min = lhs.min; max = lhs.max
    products = [min*max, min*min, max*max]
    variable.must_be.in products.min..products.max
  end

  Gecode::Raw::sqr(@model.active_space, lhs.bind, variable.bind, 
    *propagation_options)
end