# Missing values reference

> All 2 missing values in AlgoBarsX, each with its parameters, defaults, ranges and an example: nz, is_na.

Source: https://algobarsx.com/docs/ref-fn-missing-values/

### `nz(value, fallback = 0)` → like value

Replace a missing value.

#### Parameters

| Name | Type | Default | What it is |
| --- | --- | --- | --- |
| `value` | number | required | Value that may be na. |
| `fallback` | number | `0` | Replacement. |

```algobarsx
safe = nz(close[1], close)
```

Works in: strategy, indicator, alert, library. Since 1.0.

### `is_na(value)` → bool

True when a value is missing.

#### Parameters

| Name | Type | Default | What it is |
| --- | --- | --- | --- |
| `value` | number | required | Value to test. |

```algobarsx
warming_up = is_na(ema(close, 200))
```

Works in: strategy, indicator, alert, library. Since 1.0.