display("Hazi feladat")

%{
1.
%}

function result = interval_add (v1, v2)
  if (isvector(v1) && length(v1) == 2 && isvector(v2) && length(v2) == 2)
    result = v1 + v2
  else
    error ("interval_add: expecting two vector with length of 2")
  endif
endfunction

function result = interval_sub (v1, v2)
  if (isvector(v1) && length(v1) == 2 && isvector(v2) && length(v2) == 2)
    result = [v1(1) - v2(2), v1(2) - v2(1)]
  else
    error ("interval_sub: expecting two vector with length of 2")
  endif
endfunction

function result = interval_mul (v1, v2)
  if (isvector(v1) && length(v1) == 2 && isvector(v2) && length(v2) == 2)
    a = v1(1)
    b = v1(2)
    c = v2(1)
    d = v2(2)
    result = [min([a*c,a*d,b*c,b*d]), max([a*c,a*d,b*c,b*d])]
  else
    error ("interval_mul: expecting two vector with length of 2")
  endif
endfunction