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

3 次查看（过去 30 天）
Nobutaka Kim
Nobutaka Kim 2022-2-18
回答： Prateek Rai 2022-2-24
```
% 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?
  6 个评论
显示 4更早的评论
Stephen23
Stephen23 2022-2-18
编辑：Stephen23 2022-2-18
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
Jan 2022-2-18
@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.

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回答（1 个）

Prateek Rai
Prateek Rai 2022-2-24
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.

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