xy = [853704.65 1011445.66;
      852501.72 1011270.35;
      851874.53 1010783.03];
uhly = [46.4243 61.7646];

[x, y] = protinani_zpet(xy, uhly);
fprintf('x = %10.3f   y = %11.3f\n', x, y);
