# shz_inv_sqrtf_fsrra

Source: https://sh4zam.com/api/scalar/shz_inv_sqrtf_fsrra/

> Calculates 1.0f/sqrtf( x), using a fast approximation

```c
SHZ_INLINE float shz_inv_sqrtf_fsrra(float x) SHZ_NOEXCEPT;
```

Calculates 1.0f/sqrtf( `x`), using a fast approximation.

## Parameters

| Name | Type | Description |
| --- | --- | --- |
| `x` | `float` |  |

## Returns

`float`

## Naming and requirements

- `_fsrra`: Uses `FSRRA` (fast approximate 1/sqrt(x)). The argument or denominator must be positive. Faster, less precise. ([Naming and Suffixes](https://sh4zam.com/concepts/naming-and-suffixes/))

## Availability

- **C++ equivalent:** [`shz::inv_sqrtf_fsrra`](https://sh4zam.com/api/cpp/#shzinv_sqrtf_fsrra)
- **Type-generic form:** none
- **Back-ends:** SH4: dedicated SH4 implementation · SW: portable C · SPU: shared C implementation
- **Defined in:** [`sh4zam/shz_scalar.h:277`](https://github.com/gyrovorbis/sh4zam/blob/ba1e30c88d49df0311870b229e1dd860ef26c477/include/sh4zam/shz_scalar.h#L277)
- **Module:** [Scalar](https://sh4zam.com/api/scalar/), section "FSRRA"