Class: Glpk::Problem

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

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Problem

Returns a new instance of Problem.



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# File 'lib/glpk/problem.rb', line 3

def initialize
  @model = FFI.glp_create_prob
  @model.free = FFI["glp_delete_prob"]
end

Instance Method Details

#free ⇒ Object 



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# File 'lib/glpk/problem.rb', line 8

def free
  model.free = nil
  FFI.glp_delete_prob(model)
  @model = nil
end

#load_problem(obj_dir:, obj_coef:, mat_ia:, mat_ja:, mat_ar:, col_kind:, col_lower:, col_upper:, row_lower:, row_upper:) ⇒ Object 



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# File 'lib/glpk/problem.rb', line 14

def load_problem(obj_dir:, obj_coef:, mat_ia:, mat_ja:, mat_ar:, col_kind:, col_lower:, col_upper:, row_lower:, row_upper:)
  num_cols = col_lower.size
  num_rows = row_lower.size
  ne = mat_ia.size

  # some checks will always pass
  check_size(obj_coef, num_cols)
  check_size(mat_ia, ne)
  check_size(mat_ja, ne)
  check_size(mat_ar, ne)
  check_size(col_kind, num_cols)
  check_size(col_lower, num_cols)
  check_size(col_upper, num_cols)
  check_size(row_lower, num_rows)
  check_size(row_upper, num_rows)

  FFI.glp_erase_prob(model)
  FFI.glp_add_rows(model, num_rows) if num_rows > 0
  FFI.glp_add_cols(model, num_cols)

  obj_coef.each_with_index do |v, i|
    FFI.glp_set_obj_coef(model, i + 1, v)
  end
  FFI.glp_set_obj_dir(model, FFI::OBJ_DIR.fetch(obj_dir))

  # indexing starts at 1
  ia = [0] + mat_ia
  ja = [0] + mat_ja
  ar = [0] + mat_ar
  FFI.glp_load_matrix(model, ne, int_array(ia), int_array(ja), double_array(ar))

  col_kind.each_with_index do |k, i|
    FFI.glp_set_col_kind(model, i + 1, FFI::COL_KIND.fetch(k))
  end

  col_lower.zip(col_upper).each_with_index do |(lb, ub), i|
    FFI.glp_set_col_bnds(model, i + 1, 4, lb, ub)
  end

  row_lower.zip(row_upper).each_with_index do |(lb, ub), i|
    FFI.glp_set_row_bnds(model, i + 1, row_type(lb, ub), lb, ub)
  end
end

#read_lp(filename) ⇒ Object 



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# File 'lib/glpk/problem.rb', line 58

def read_lp(filename)
  check_status FFI.glp_read_lp(model, nil, filename)
end

#read_mps(filename) ⇒ Object 



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# File 'lib/glpk/problem.rb', line 62

def read_mps(filename)
  check_status FFI.glp_read_mps(model, 2, nil, filename)
end

#solve(**options) ⇒ Object 



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# File 'lib/glpk/problem.rb', line 74

def solve(**options)
  if FFI.glp_get_num_int(model) > 0
    solve_mip(**options)
  else
    solve_lp(**options)
  end
end

#write_lp(filename) ⇒ Object 



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# File 'lib/glpk/problem.rb', line 66

def write_lp(filename)
  check_status FFI.glp_write_lp(model, nil, filename)
end

#write_mps(filename) ⇒ Object 



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# File 'lib/glpk/problem.rb', line 70

def write_mps(filename)
  check_status FFI.glp_write_mps(model, 2, nil, filename)
end