Matlab is not recognizing that two floats are equal although Workspace shows they are

```

% calculate_line_lengths

line_lengths = calculate_line_lengths(plane_x,plane_y, rect_corners);

% send the above two answers to herons_formula, get 4 areas

four_areas = herons_formula(edge_lengths, line_lengths);

sum_four_areas = sum(four_areas);

if sum_four_areas == rect_area

in_rect = true;

elseif sum_four_areas < rect_area

in_rect = false;

end

```

My code falls into the elseif when it should be going into the if statement as they are equal.

Why?

[per isakson]

See Why is (2.24*10)-22.4 not equal to 0?

[Stephen23]

"why"

Because the values are not equal.

Question: if the values differ for example in the 10th fractional digit, would you see that difference when you simply look at the values displayed to 4 fractional digits? (hint: no, you would not).

[Nobutaka Kim]

is there something like an np.isclose() from Python?

[Walter Roberson]

ismembertol

[Stephen23]

Where A and B are the two values you wish to compare, and tol is a suitably chosen tolerance value:

abs(A-B)<tol

[Jan]

@Walter Roberson: Until today, the method ismembertol has implemented the tolerance, did never match my needs in real code:

abs(u-v) <= tol*max(abs([A(:);B(:)]))

'DataScale' is not a solution also.

Answer 1

[Prateek Rai]

You can refer to following MATLAB Answers on Why two equal numbers are not equal? to get more idea on why MATLAB is not recognizing that two floats are equal although workspace shows that they are equal.