Class: MIPPeR::LPSolveModel

Inherits:
Model
  • Object
show all
Defined in:
lib/mipper/lp_solve/model.rb

Overview

A linear programming model using the lp_solve solver

Instance Attribute Summary collapse

Attributes inherited from Model

#constraints, #variables

Instance Method Summary collapse

Methods inherited from Model

#<<, #compute_iis, #objective_value, #status, #update, #variable_value, #write_lp, #write_mps

Constructor Details

#initialize ⇒ LPSolveModel

Returns a new instance of LPSolveModel.



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# File 'lib/mipper/lp_solve/model.rb', line 6

def initialize
  fail unless MIPPeR.const_defined?(:LPSolve)

  super

  @var_count = 0
  @constr_count = 0

  # Construct a new model
  @ptr = FFI::AutoPointer.new LPSolve.make_lp(0, 0),
                              LPSolve.method(:delete_lp)

  # Disable output
  ret = LPSolve.set_outputfile @ptr, ''
  fail if ret != 1
end

Instance Attribute Details

#ptr ⇒ Object (readonly)

Returns the value of attribute ptr.



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# File 'lib/mipper/lp_solve/model.rb', line 4

def ptr
  @ptr
end

Instance Method Details

#optimize ⇒ Object

Optimize the model



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# File 'lib/mipper/lp_solve/model.rb', line 31

def optimize
  # Ensure pending variables and constraints are added
  update

  # Run the solver and save the status for later
  status = LPSolve.solve(@ptr)
  save_solution status
end

#sense=(sense) ⇒ Object

Set the sense of the model



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# File 'lib/mipper/lp_solve/model.rb', line 24

def sense=(sense)
  @sense = sense
  sense = sense == :min ? 0 : 1
  LPSolve.set_sense @ptr, sense
end

#set_variable_bounds(var_index, lb, ub) ⇒ Object 



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# File 'lib/mipper/lp_solve/model.rb', line 40

def set_variable_bounds(var_index, lb, ub)
  ret = LPSolve.set_bounds @ptr, var_index, lb, ub
  fail if ret != 1
end