The code does not work with 1.7

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

[Wayne King]

what are you trying to do with this code???

[net]

I wanted to count elements.

1.3 => 3 times

1.7 => 2 times etc.

These answers solved my problem.

Thanks for the all of answers.

Answer 1

[Titus Edelhofer]

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

[Andrei Bobrov]

sum(y == i1) -> sum(abs(y-i1) < 100*eps)

Answer 2

[Robert Cumming]

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

Answer 3

[Junaid]

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].

Answer 4

[net]

Thanks for the answers.