If statement in for loop does not work
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I am trying to model a particle bouncing around in a box. The size of the box is 0<=x<=1 and 0<=y<=1. so given an initial position and velocity the particle will move until it hits a wall and then it bounces. I have an idea of how this should work but as I was working through the project I hit this problem. This is a simplified version of the code that is causing the problem. the value of x is 1 at some point in the iteration but the if statement doesnt recognmize it.
x = 0.5;
for i=1:6
x = x+0.1
if x == 1
disp('yes')
end
end
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Antworten (2)
KALYAN ACHARJYA
am 9 Feb. 2021
Bearbeitet: KALYAN ACHARJYA
am 9 Feb. 2021
It's because floating point numbers representation (Exactly). Hence If you're trying to do logical comparision (==) with floating-point numbers, be careful.
Please refer the following
More:
But if you are insisted to way out, you may consider difference between the numbers as allowable tolerance (error) and use > or < logical comparision in the "if statement".
Hope it Helps!
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randerss simil
am 9 Feb. 2021
%if true
x = 0.5;
for i=1:6
x = (x)+0.1
if strcmp(num2str(x),'1')
disp('yes')
end
end
Try the above
1 Kommentar
Jan
am 9 Feb. 2021
Letting strcmp perform a rounding is a very indirect and instable way. The actual poblem of floating point number is not addressed here. Using a limit for the numeric comparison is better: if abs(x - 1) < 10 * eps
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