# Why is 1.0f-99 not a subnormal number?

**URL:** https://discourse.julialang.org/t/why-is-1-0f-99-not-a-subnormal-number/120833
**Category:** General Usage
**Tags:** question
**Created:** [October 2, 2024, 11:43pm UTC](https://discourse.julialang.org/t/why-is-1-0f-99-not-a-subnormal-number/120833 "2024-10-02T23:43:24Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![StevenSiew](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stevensiew/32/218393_2.png) [@StevenSiew](https://discourse.julialang.org/u/StevenSiew)
#### Post date: [October 2, 2024, 11:43pm UTC](https://discourse.julialang.org/t/why-is-1-0f-99-not-a-subnormal-number/120833/1 "2024-10-02T23:43:24Z")

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```julia
ulia> issubnormal(1.0f-37)
false

julia> issubnormal(1.0f-38)
true

julia> issubnormal(1.0f-39)
true

julia> issubnormal(1.0f-99)
false

```

For Float64 numbers subnormal starts from exponent -308 to -324 and then it stops

```julia
julia> issubnormal(5.0e-308)
false

julia> issubnormal(5.0e-309)
true

julia> issubnormal(5.0e-310)
true

julia> issubnormal(5.0e-324)
true

julia> issubnormal(5.0e-325)
false

```

The question is why?

---

<div class="post-metadata">

### Author: ![johnmyleswhite](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/johnmyleswhite/32/31_2.png) [@johnmyleswhite](https://discourse.julialang.org/u/johnmyleswhite)
#### Post date: [October 2, 2024, 11:48pm UTC](https://discourse.julialang.org/t/why-is-1-0f-99-not-a-subnormal-number/120833/2 "2024-10-02T23:48:07Z")

</div>

> [@StevenSiew](#):
>
> `1.0f-99`

Because `1.0f-99` is actually a literal for `0.0f0`, which is not subnormal since `0.0` is never subnormal.