The code does not work with 1.7
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This code works normally accept 1.7
it does not count 1.7
I coul not understand why
y=[1.3,1.3,1.7,1.3,1.7,1.6,1.8,1.9,1.6]; %y=[1.7,1.7,1.7,1.7,1.7,1.7,1.7,1.7,1.7]; x=1;
for i=1:0.1:1.9
v(x)=sum(y==i);
x=x+1;
end
v
采纳的回答
Titus Edelhofer
2011-11-30
Hi,
this is due to roundoff: 0.1 is not representable as a finite number in binary system. Note the following:
i=1:0.1:1.9;
i(9)-1.8
ans =
-2.2204e-016
And then your test on equality fails ...
Titus
1 个评论
Andrei Bobrov
2011-11-30
sum(y == i1) -> sum(abs(y-i1) < 100*eps)
更多回答（3 个）
Robert Cumming
2011-11-30
As said above you have encountered the problem of floating point arithmetic, if change your counter to be 1 instead of 0.1 (and change your inner the line to:
v = sum (y==i/10)
you will see 1.7 is counted.
Its worth understanding that computer are not exact due to the way they store information in memory, for example try:
[0.3-0.2 == 0.1]
[0.3-0.2-0.1]
They answers are not what you might expect... Note this is not a problem of Matlab alone. Have a read of this answer
Junaid
2011-11-30
Anyway you can do what ever you want from this simple one lines.
v =hist(y,[1:.1:2])
This is simple. Take the histgram. The number of bins are decided by [1:.1:2].
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