c# Use of unassigned local variable hatası yardım.

using System; 
  using System.Collections.Generic; 
  using System.ComponentModel; 
  using System.Data; 
  using System.Drawing; 
  using System.Linq; 
  using System.Text; 
  using System.Windows.Forms; 
   
  namespace WindowsFormsApplication1 
  { 
      public partial class Form1 : Form 
      { 
          public Form1() 
          { 
          } 
   
          private void Form1_Load(object sender, EventArgs e) 
          { 
   
          } 
   
          private void button1_Click(object sender, EventArgs e) 
          { 
              comboBox1.Items.Clear(); 
              comboBox2.Items.Clear(); 
              comboBox3.Items.Clear(); 
              int NS; 
              int NA; 
              double SMALL; 
              NA = 2; 
              NS = 2; 
              double[, ,] tpm = new double[NA - 1, NS - 1, NS - 1]; 
              double[, ,] trm = new double[NA - 1, NS - 1, NS - 1]; 
              SMALL = -100000; 
              tpm[0, 0, 0] = 0.7; 
              tpm[0, 0, 1] = 0.3; 
              tpm[0, 1, 0] = 0.4; 
              tpm[0, 1, 1] = 0.6; 
              tpm[1, 0, 0] = 0.9; 
              tpm[1, 0, 1] = 0.1; 
              tpm[1, 1, 0] = 0.2; 
              tpm[1, 1, 1] = 0.8; 
              trm[0, 0, 0] = 6; 
              trm[0, 0, 1] = -5; 
              trm[0, 1, 0] = 7; 
              trm[0, 1, 1] = 12; 
              trm[1, 0, 0] = 10; 
              trm[1, 0, 1] = 17; 
              trm[1, 1, 0] = -14; 
              trm[1, 1, 1] = 13; 
   
              int state, next_state, iteration, done, row, col, action, best_action; 
              int[] policy = new int[NS - 1]; 
              double[,] G = new double[NS - 1, NS]; 
              double[] x = new double[NS - 1]; 
              double large, sum, rho; 
              for (state = 0; state <= NS - 1; state++) 
              { 
                  policy[state] = 0; 
              } 
              iteration = 0; 
              done = 1; 
   
   
              while (done == 1) 
              { 
                  for (row = 0; row <= NS - 1; row++) 
                  { 
                      for (col = 0; col <= NS - 1; col++) 
                      { 
                          if (col == 0) 
                          { 
                              G[row, col] = 1; 
                          } 
                          else 
                          { 
                              if (row == col) 
                              { 
                                  G[row, col] = 1 - tpm[policy[row], row, col]; 
                              } 
                              else 
                              { 
                                  G[row, col] = -tpm[policy[row], row, col]; 
                              } 
                          } 
                      } 
                  } 
   
                  for (state = 0; state <= NS - 1; state++) 
                  { 
                      sum = 0; 
                      for (next_state = 0; next_state <= NS - 1; next_state++) 
                      { 
                          sum = sum + (tpm[policy[state], state, next_state] * trm[policy[state], state, next_state]); 
                      } 
                      G[state, NS] = sum; 
                  } 
                  ///Solver 
                  int row_a, col_a, row1_a, col2_a, col1_a,pivot_row_a; 
                  double factor_a, pivot_a, temp_a; 
                  for (col_a = 0; col_a <= NS - 1; col_a++) 
   
                  { 
                      pivot_a = -0.1; 
   
                       
                      for (row_a = col_a; row_a <= NS - 1; row_a++) 
   
                      { 
                          if (Math.Abs(G[row_a, col_a]) > pivot_a) 
                          { 
   
                              pivot_a = Math.Abs(G[row_a, col_a]); 
                              pivot_row_a = row_a; 
                          } 
                      } 
                      if (pivot_a <= 1E-05) 
                      { 
                          break; 
                      } 
                    ************************* if (pivot_row_a != col_a)************************* 
                      { 
                          for (col1_a = col_a; col1_a <= NS; col1_a++) 
                          { 
                              temp_a = G[col_a, col1_a]; 
                              G[col_a, col1_a] = G[pivot_row_a, col1_a]; 
                              G[pivot_row_a, col1_a] = temp_a; 
                          } 
                      } 
                      for (row1_a = 0; row1_a <= NS - 1; row1_a++) 
                      { 
                          if (row1_a != col_a) 
                          { 
                              factor_a = G[row1_a, col_a] / G[col_a, col_a]; 
                              for (col2_a = col_a; col2_a <= NS; col2_a++) 
                              { 
                                  G[row1_a, col2_a] = G[row1_a, col2_a] - factor_a * G[col_a, col2_a]; 
                              } 
                          } 
                      } 
                  } 
                  for (row_a = 0; row_a <= NS - 1; row_a++) 
                  { 
                      x[row_a] = G[row_a, NS] / G[row_a, row_a]; 
                  } 
   
   
   
                  rho = x[0]; 
                  comboBox1.Items.Add(Convert.ToString(iteration) + ",    " + Convert.ToString(x[0])); 
                  x[0] = 0; 
                  done = 0; 
   
                  for (state = 0; state <= NS - 1; state++) 
                  { 
                      large = SMALL; 
                      best_action = 0; 
                      for (action = 0; action <= NA - 1; action++) 
                      { 
                          sum = 0; 
                          for (next_state = 0; next_state <= NS - 1; next_state++) 
                          { 
                              sum = sum + (tpm[action, state, next_state] * (trm[action, state, next_state] + x[next_state])); 
                          } 
                          if (sum > large) 
                          { 
                              large = sum; 
                              best_action = action; 
                          } 
                      } 
                      if (policy[state] != best_action) 
                      { 
                          policy[state] = best_action; 
                          done = 1; 
                      } 
                  } 
   
                  iteration = iteration + 1; 
              } 
   
              for (state = 0; state <= NS - 1; state++) 
              { 
                  comboBox2.Items.Add(Convert.ToString(state + 1) + ",   " + Convert.ToString(policy[state] + 1)); 
              } 
              for (state = 0; state <= NS - 1; state++) 
              { 
                  comboBox2.Items.Add(Convert.ToString(state + 1) + ",    " + Convert.ToString(x[state])); 
              } 
              textBox1.Text = "İterasyon Sayısı = " + iteration; 
          } 
   
          private void button2_Click(System.Object sender, System.EventArgs e) 
          { 
              Activate(); 
          } 
      } 
  }