int &ix, int &iy, Point location)

{

// adjust with origin and scale

Cartesian_vector subscripts = (location - origin) / scale;

// truncate coordinates to integer after taking the floor

// floor function will return the largest integer smaller than the supplied value

// even for negative values, so -0.05 => -1., which will be outside the array.

ix = int(floor(subscripts.delta_x));

iy = int(floor(subscripts.delta_y));

// if out of range, return false

if ((ix < 0) || (ix >= size) || (iy < 0) || (iy >= size)) {

return false;

} else {

return true;

}