void circleArrayStim(float leftCornerX, float leftCornerY, int rows, int columns, int diameter, float space){  
  for (int rowNum = 0; rowNum < rows; rowNum ++){
    for (int colNum = 0; colNum < columns; colNum++){
      fill(color(0,20,0));
      ellipseMode(CENTER);
      ellipse(convertXCoord(leftCornerX) + colNum*(diameter+space), 
              convertYCoord(leftCornerY) + rowNum*(diameter+space), diameter, diameter);
    }
  }
}