---
title: "evaluate(x:)"
framework: phase
role: symbol
role_heading: Instance Method
path: "phase/phaseenvelope/evaluate(x:)"
---

# evaluate(x:)

Provides the height of the envelope for an input value.

## Declaration

```swift
func evaluate(x: Double) -> Double
```

## Parameters

- `x`: A value within the envelope’s domain. The envelope clamps this parameter to a value within doc://com.apple.phase/documentation/PHASE/PHASEEnvelope/domain.

## Return Value

Return Value The curve’s height for the argument x value.

## See Also

### Inspecting the Envelope

- [segments](phase/phaseenvelope/segments.md)
- [startPoint](phase/phaseenvelope/startpoint.md)