MATLAB: Strange issue with if expression, failing to compare two variables properly

comparing variables

Hi I'm having this small snippet, i'm finding values of coordinates as Lx1 and Lx2. they are same but if condition is jumping out to else clause! i've no clue on why its happening am i missing something obvious!
%%
    line1 = [2 5 0 ; 9 1 0 ];
    line2 = [1 1 0  ; 13 13 0];
    line1_vector = ( line1(2,:) - line1(1,:))  / sqrt ( sum((line1(1,:)-line1(2,:) ).^2));
    line2_vector = (line2(2,:) - line2(1,:)) / sqrt ( sum((line2(2,:)-line2(1,:) ).^2));
    matrix_A = [ line1_vector(1:2)'   -1*line2_vector(1:2)'];
    matrix_b = [line2(1,1:2)' - line1(1,1:2)'];
    parameter_matrix = matrix_A\ matrix_b;
    Lz1 = line1(1,3) + parameter_matrix(1)*line1_vector(3)
    Ly1 = line1(1,2) + parameter_matrix(1)*line1_vector(2);
    Lx1 = line1(1,1) + parameter_matrix(1)*line1_vector(1)
    Lz2 = line2(1,3) + parameter_matrix(2)*line2_vector(3)
    Ly2 = line2(1,2) + parameter_matrix(2)*line2_vector(2);
    Lx2 = line2(1,1) + parameter_matrix(2)*line2_vector(1)
    if (Lz1==Lz2)
        if (Lx1==Lx2)
            status =0
        else
            status =1
        end
    end

Best Answer

I doubt they are the same. Even if they are meant to be the same, there are bound to be small floating point round-off errors making them different. Use a tolerance,
 if abs(Lx1-Lx2)<somethingsmall
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