Why does this algorithm yield an 'incorrect' result?

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Lewis
Lewis 2022-1-18
编辑： DGM 2022-1-18
The following code yields cumul_total = 2.000000000026658e+05 . What is the '26658' on the end? Why does this occur?
Thank you
A = (0.2);
cumul_total = (0.0);
for iii = 1:1e6
cumul_total = cumul_total + A;
end
cumul_total

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DGM
DGM 2022-1-18
编辑：DGM 2022-1-18
This is a consequence of accumulating the small errors inherent to floating-point representations of numbers.
A = 0.2;
S = 0;
% watch the error
format long
for k = 1:100
S = S+A
end
Note the remarks on accuracy and pitfalls here.
https://www.mathworks.com/help/matlab/matlab_prog/floating-point-numbers.html#f2-98690

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