---
title: math.is_subnormal
summary: null
url: >-
  https://www.fastly.com/documentation/reference/vcl/functions/floating-point-classifications/math-is-subnormal
---

```
BOOL math.is_subnormal(FLOAT x)
```

**Available in:** all subroutines

Determines whether a floating point value is _subnormal_. See
[floating point classifications](https://www.fastly.com/documentation/reference/vcl/functions/floating-point-classifications/) for
more information.

## Example

```vcl
declare local var.f FLOAT;

set var.f = math.FLOAT_MIN; # minimum finite value
if (!math.is_subnormal(var.f)) {
  log "not subnormal";
}
set var.f /= 2;
if (math.is_subnormal(var.f)) {
  log "subnormal";
}
```