Compute the ATT distance between two points (see TSPLIB documentation)

def distATT(x1,y1,x2,y2):
    """Compute the ATT distance between two points (see TSPLIB documentation)"""
    xd = x2 - x1
    yd = y2 - y1
    rij = math.sqrt((xd*xd + yd*yd) /10.)
    tij = int(rij + .5)
    if tij < rij:
        return tij + 1
    else:
        return tij