Quick Float question

Ruby
1

I’m doing some math with Ruby and I’d really like to know why:

irb(main):002:0> 10.0 / 3.0
=> 3.33333333333333

but

irb(main):003:0> (10.0 / 3.0) == 3.33333333333333

is

=> false

Thanks :slight_smile:

Cliff

2

This is because the 3.33333333333333 is not the exact value you got
from 10.0/3.0. Ruby store more information you can’t not see.
So if you want to compare the float, you can write it as
(10.0/3.0 - 3.3333333333).abs <= 0.0001

3

Hank G. wrote:

This is because the 3.33333333333333 is not the exact value you got
from 10.0/3.0. Ruby store more information you can’t not see.
So if you want to compare the float, you can write it as
(10.0/3.0 - 3.3333333333).abs <= 0.0001

This is what I thought. Thanks for clarifying that. I need it
primarily for unit testing, I’ll try this technique and see how I go.

Thanks again

Cliff

4

On 8/10/07, Cliff R. [email protected] wrote:

Hank G. wrote:

This is because the 3.33333333333333 is not the exact value you got
from 10.0/3.0. Ruby store more information you can’t not see.
So if you want to compare the float, you can write it as
(10.0/3.0 - 3.3333333333).abs <= 0.0001

This is what I thought. Thanks for clarifying that. I need it
primarily for unit testing, I’ll try this technique and see how I go.

assert_in_delta 3.3333333333, 10.0/3.0, 0.0001

-greg

5

Gregory B. wrote:

assert_in_delta 3.3333333333, 10.0/3.0, 0.0001

-greg

Perfect, thankyou :slight_smile:

Cliff