「GLPK for C#/CLIで遊ぼう！ - Qiita」( http://qiita.com/YSRKEN/items/408c0aac09bbb8034eb2 ) 用に書いたプログラム

glpk_sample2.cs

using org.gnu.glpk;

namespace GlpkSample {
	class Program {
		// デバッガ出力
		void ShowMIP(glp_prob mip) {
			string lp_file = "";
			// 目的関数
			lp_file += (GLPK.glp_get_obj_dir(mip) == GLPK.GLP_MIN ? "minimize" : "maximize") + "\n";
			var colCount = GLPK.glp_get_num_cols(mip);
			for(int i = 1; i <= colCount; ++i) {
				var coef = GLPK.glp_get_obj_coef(mip, i);
				lp_file += " " + (coef >= 0.0 ? "+" : "") + coef.ToString() + " x" + i.ToString();
			}
			lp_file += "\n";
			// 制約式
			lp_file += "subject to\n";
			var rowCount = GLPK.glp_get_num_rows(mip);
			var ind = GLPK.new_intArray(colCount + 1);
			var val = GLPK.new_doubleArray(colCount + 1);
			for(int i = 1; i <= rowCount; ++i) {
				var subject = "";
				var len1 = GLPK.glp_get_mat_row(mip, i, null, null);
				var len = GLPK.glp_get_mat_row(mip, i, ind, val);
				var coef = new List<double>();
				for(int j = 0; j < colCount; ++j) {
					coef.Add(0.0);
				}
				for(int j = 1; j <= len; ++j) {
					coef[GLPK.intArray_getitem(ind, j) - 1] = GLPK.doubleArray_getitem(val, j);
				}
				for(int j = 0; j < colCount; ++j) {
					subject += " " + (coef[j] >= 0.0 ? "+" : "") + coef[j].ToString() + " x" + (j + 1).ToString();
				}
				var type = GLPK.glp_get_row_type(mip, i);
				var lb = GLPK.glp_get_row_lb(mip, i);
				var ub = GLPK.glp_get_row_ub(mip, i);
				if(type == GLPK.GLP_FR) {
					//
				}else if(type == GLPK.GLP_LO) {
					lp_file += subject + " >= " + lb;
				}else if(type == GLPK.GLP_UP) {
					lp_file += subject + " <= " + ub;
				}else if(type == GLPK.GLP_DB) {
					lp_file += subject + " >= " + lb + "\n";
					lp_file += subject + " <= " + ub;
				} else {
					lp_file += subject + " = " + lb;
				}
				lp_file += "\n";
			}
			// 変数制約
			lp_file += "bounds\n";
			for(int i = 1; i <= colCount; ++i) {
				var type = GLPK.glp_get_col_type(mip, i);
				var lb = GLPK.glp_get_col_lb(mip, i);
				var ub = GLPK.glp_get_col_ub(mip, i);
				if(type == GLPK.GLP_FR) {
					lp_file += "x" + i.ToString() + " free";
				} else if(type == GLPK.GLP_LO) {
					lp_file += "x" + i.ToString() + " >= " + lb;
				} else if(type == GLPK.GLP_UP) {
					lp_file += "x" + i.ToString() + " <= " + ub;
				} else if(type == GLPK.GLP_DB) {
					lp_file += " " + lb + " <= x" + i.ToString() + " <= " + ub;
				} else {
					lp_file += "x" + i.ToString() + " = " + lb;
				}
				lp_file += "\n";
			}
			lp_file += "general\n";
			for(int i = 1; i <= colCount; ++i) {
				var type = GLPK.glp_get_col_kind(mip, i);
				if(type == GLPK.GLP_IV) {
					lp_file += " x" + i;
				}
			}
			lp_file += "\n";
			lp_file += "binary\n";
			for(int i = 1; i <= colCount; ++i) {
				var type = GLPK.glp_get_col_kind(mip, i);
				if(type == GLPK.GLP_BV) {
					lp_file += " x" + i;
				}
			}
			lp_file += "\n";
			GLPK.delete_intArray(ind);
			GLPK.delete_doubleArray(val);
			Console.WriteLine(lp_file);
		}
  }
}