Min max coordinate of cells, given cell length in C #

Please see attached photo to better understand my question

i has a matrix of cells [JXI], a cell has a square shape with length "a"

my question is, is there a way to use a FOR loop to assign MIN, MAX coordinates to each cell, taking origin (0,0) at one corner

thanks

image http://img199.imageshack.us/img199/3544/pixelv.png

I tried to execute the following code but no time

int a ; 
a = 1;
for (int J=1; J<=5; J++)
{
  for (int I = 1; I <= 5; I++)
  {
    double Xmin = ((I - 1)*a );
    double Ymin = ((J - 1) * a);
    double Xmax = (I * a );
    double Ymax = (J * a);
  }
}