# `GSCurveIsFlatError`

*Function*

## Declaration

```swift
func GSCurveIsFlatError(_ on1: NSPoint, _ off1: NSPoint, _ off2: NSPoint, _ on2: NSPoint, _ flatError: CGFloat) -> Bool
```

```objc
BOOL GSCurveIsFlatError(NSPoint on1, NSPoint off1, NSPoint off2, NSPoint on2, CGFloat flatError);
```

```python
GSCurveIsFlatError(on1: NSPoint, off1: NSPoint, off2: NSPoint, on2: NSPoint, flatError: float) -> bool
```

## See Also

### Curve Parameters and Solvers

- [`GSCalcCubicParameters`](/Core/GlyphsCore/GSCalcCubicParameters)
- [`GSCalcQuadraticParameters`](/Core/GlyphsCore/GSCalcQuadraticParameters)
- [`GSSolveQuadratic`](/Core/GlyphsCore/GSSolveQuadratic)
- [`GSSolveCubic`](/Core/GlyphsCore/GSSolveCubic)
- [`GSDividLineAtDistance`](/Core/GlyphsCore/GSDividLineAtDistance)
- [`GSExtendCurvePoints`](/Core/GlyphsCore/GSExtendCurvePoints)
- [`GSFitCurveToOriginPoints`](/Core/GlyphsCore/GSFitCurveToOriginPoints)
- [`GSFitCurveToOriginPointsDirection`](/Core/GlyphsCore/GSFitCurveToOriginPointsDirection)
- [`GSCurveIsFlat`](/Core/GlyphsCore/GSCurveIsFlat)