set xrange [0:3000] set yrange [0:2100] tdoa (x, y, x0, y0, x1, y1) = sqrt ((x - x0)**2 + (y - y0)**2) - sqrt ((x - x1)**2 + (y - y1)**2) tdoa_b12 (x, y) = tdoa (x, y, 3000, 0, 3000, 2100) tdoa_b23 (x, y) = tdoa (x, y, 3000, 0, 0, 1050) tdoa_b31 (x, y) = tdoa (x, y, 3000, 2100, 0, 1050) set contour set cntrparam levels 50 unset surface set view map unset clabel set term png set output 'tdoa-large.png' splot tdoa_b12 (x, y), tdoa_b23 (x, y), tdoa_b31 (x, y)