unique() returns duplicate values in the beginning of the array

I ran this line

struct1.points = unique([0:.00001:struct2.highbound struct2.highbound])';

then I opened struct1.points and I saw the first two elements are both 0. I tried to copy the two elements and paste outside Matlab to see if they're strict 0s and the answer is yes -- both are exactly equal to 0. The array looks like this:

0

0

2.00000000000000e-05

3.00000000000000e-05

4.00000000000000e-05

5.00000000000000e-05

5.99999999999999e-05

7.00000000000000e-05

But theoretically the second element should be 1.0000e-05 and there should not be duplicate values. Why is that not the case? Any thoughts appreciated.Thanks.

Answer 1

[Star Strider]

They’re actually not both zero.

See: Why is 0.3 - 0.2 - 0.1 (or similar) not equal to zero?

[Walter Roberson]

And use

format long g

so you can see the entire value.

[Star Strider]

Thank you, Walter!

I overlooked that.

[Jenny Shu]

No they're both 0. I copied these two numbers and pasted outside Matlab. There's no digits after the 0.

[Walter Roberson]

>> format long g
>> struct2.highbound = (pi/1000);struct1.points = unique([0:.00001:struct2.highbound struct2.highbound])';
>> size(struct1.points)

ans =

     316     1

>> struct1.points(1:10)

ans =

                           0
                       1e-05
                       2e-05
                       3e-05
                       4e-05
                       5e-05
                       6e-05
                       7e-05
                       8e-05
                       9e-05