Objective-C(iPhone SDK) - Code for Chemical Equation Balancer help
- by Evan
-(IBAction) balancer: (id) sender{
 double M[4][4];
 M[0][0] = 6.0;
 M[0][1] = 0.0;
 M[0][2] = -1.0;
 M[0][3] = 0.0;
 M[1][0] = 12.0;
 M[1][1] = 0.0;
 M[1][2] = 0.0;
 M[1][3] = 2.0;
 M[2][0] = 6.0;
 M[2][1] = 2.0;
 M[2][2] = -2.0;
 M[2][3] = 1.0;
 M[3][0] = 0.0;
 M[3][1] = 0.0;
 M[3][2] = 0.0;
 M[3][3] = 0.0;
 int rowCount = 4;
int columnCount = 4;
int lead = 0;
 for (int r = 0; r < rowCount; r++) {
  if (lead = columnCount)
   break;
int i = r;
  while (M[i][lead] == 0) {
   i++;
   if (i == rowCount) {
    i = r;
    lead++;
    if (lead == columnCount){
 break;
}
}
  }
  double temp[4] ;
  temp[0] = M[r][0];
  temp[1] = M[r][1];
  temp[2] = M[r][2];
  temp[3] = M[r][3];
  M[r][0] = M[i][0];
  M[r][1] = M[i][1];
  M[r][2] = M[i][2];
  M[r][3] = M[i][3];
  M[i][0] = temp[0];
  M[i][1] = temp[1];
  M[i][2] = temp[2];
  M[i][3] = temp[3];
double lv = M[r][lead];
  for (int j = 0; j < columnCount; j++)
   M[r][j] = M[r][j] / lv;
for (int f = 0; f < rowCount; f++) {
   if (f != r) {
    double l = M[f][lead];
    for (int j = 0; j < columnCount; j++)
     M[f][j] =  M[f][j] - l * M[r][j];
   }
  }
  lead++;
}
NSString* myNewString = [NSString stringWithFormat:@"%g",M[0][3]]; 
label1.text = myNewString;
}
This is returning NaN, while it should be returning .16666667 for M[0][3]. Any suggestions on how to fix this?