Loop Trough Time t = t+dt
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I have a simple code like this
t = 1380;
dt = 0.1
for i = 1:1000
t = t+dt;
disp(t)
end
I believe the answer should be obvious that the final answer should be
t = 1480. I dont know why Matlab shows the answer a little bit different which is 1479.99999999991.
Anyone know why?
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Respuestas (1)
Star Strider
el 13 de Nov. de 2019
You have encountered floating-point approximation error.
3 comentarios
Star Strider
el 18 de Nov. de 2019
Yes.
Change it to:
if abs(t - 1400) < 0.05
a = 2
end
Since the code counts up by ‘dt’, this will introduce a tolerance in the calculation, so the floating-point approximation error are taken into account.
To see this graphically:
t = linspace(1399, 1401);
figure
plot(t, (abs(t - 1400) < 0.05))
grid
That will show the effect of using the inequality to test for a range of values for ‘t’ near 1400.
Experiment to get the result you want.
darova
el 18 de Nov. de 2019
Don't use equal sign for float numbers
if abs(t-1400) < 1e-6 % tolerance
a = 2;
end
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