set xrange [-1000:1000] set yrange [-1000:1000] tdoa (x, y, x0, y0, x1, y1) = sqrt ((x - x0)**2 + (y - y0)**2) - sqrt ((x - x1)**2 + (y - y1)**2) set isosamples 50 set pm3d unset surface set term png set output 'tdoa-small_tm3d.png' splot tdoa (x, y, 4, -4, -4, 4) set contour set cntrparam levels 15 unset pm3d set view map unset clabel set term png set output 'tdoa-small_contour.png' #splot tdoa (x, y, -4, -4, 4, 4), tdoa (x, y, -4, 4, 4, -4) #splot tdoa (x, y, -15, 0, -10, 0), tdoa (x, y, 15, 0, 10, 0) splot tdoa (x, y, -15, 0, -11, -4), tdoa (x, y, 15, 0, 15, -4) #set cntrparam levels discrete 8.42638136229502 #set cntrparam levels discrete 2.99544039802068 #set cntrparam levels discrete 5.43094096427434 #splot tdoa (x, y, -4, -4, 0, 4), tdoa (x, y, 4, -4, 0, 4), tdoa (x, y, -4, -4, 4, -4)