Class: Quicopt::Constraint

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

Overview

One constraint row: a residual expression compared against zero.

expr is lhs - rhs, so the row is expr <= 0, expr >= 0 or expr == 0. Quicopt::Wire then splits that into the body (the variable terms) and the numeric bound (the constant, moved to the other side), which is the form Quicopt sends.

Constant Summary collapse

SENSES =

The comparison operator each sense renders as.

{ le: "<=", ge: ">=", eq: "==" }.freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(expr, sense) ⇒ Constraint

Returns a new instance of Constraint.

Raises:

  • (ArgumentError) 


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# File 'lib/quicopt/model.rb', line 414

def initialize(expr, sense)
  raise ArgumentError, "unknown constraint sense #{sense.inspect}" unless SENSES.key?(sense)

  @expr = expr
  @sense = sense
  freeze
end

Instance Attribute Details

#expr ⇒ Expression (readonly)

Returns the residual lhs - rhs.

Returns:



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# File 'lib/quicopt/model.rb', line 405

def expr
  @expr
end

#sense ⇒ Symbol (readonly)

Returns :le, :ge or :eq.

Returns:

  • (Symbol) —

    :le, :ge or :eq



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# File 'lib/quicopt/model.rb', line 407

def sense
  @sense
end

Class Method Details

.build(lhs, rhs, sense) ⇒ Object

Build a row from the two sides of a comparison.



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# File 'lib/quicopt/model.rb', line 410

def self.build(lhs, rhs, sense)
  new(Expression.cast(lhs).plus(Expression.cast(rhs).scale(-1.0)), sense)
end

Instance Method Details

#body ⇒ Expression

The row body: the variable terms alone, with the constant moved to bound.

Returns:



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# File 'lib/quicopt/model.rb', line 425

def body
  Expression.new(linear: @expr.linear, quadratic: @expr.quadratic)
end

#bound ⇒ Float

The right-hand side after moving the constant across.

Returns:

  • (Float) 


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# File 'lib/quicopt/model.rb', line 432

def bound
  -@expr.constant
end

#inspect ⇒ String

Returns the row, tagged with the class.

Returns:

  • (String) —

    the row, tagged with the class



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# File 'lib/quicopt/model.rb', line 442

def inspect
  "#<Quicopt::Constraint #{self}>"
end

#to_s ⇒ Object

Renders the row as body <op> bound.



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# File 'lib/quicopt/model.rb', line 437

def to_s
  "#{body} #{SENSES[@sense]} #{Format.number(bound)}"
end