---
title: "+=(_:_:)"
framework: spatial
role: symbol
role_heading: Operator
path: "spatial/size3dfloat/+=(_:_:)-7eiud"
---

# +=(_:_:)

Calculates the element-wise sum of two sizes and stores the result in the left-hand-side variable.

## Declaration

```swift
static func += (lhs: inout Size3DFloat, rhs: Size3DFloat)
```

## Parameters

- `lhs`: The first value.
- `rhs`: The second value.