---
title: rtol
framework: accelerate
role: symbol
role_heading: Instance Property
path: accelerate/sparsecgoptions/rtol
---

# rtol

The relative convergence tolerance.

## Declaration

```swift
var rtol: Double
```

## Discussion

Discussion ‖ b-Ax ‖₂ < * ‖ b-Ax₀ ‖₂ + atol indicates convergence. If rtol is equal to 0, the operation uses the default value of sqrt(epsilon). If it’s negative, the operation treats rtol as 0.0 (it doesn’t use the default).

## See Also

### Inspecting CG Options

- [atol](accelerate/sparsecgoptions/atol.md)
- [maxIterations](accelerate/sparsecgoptions/maxiterations.md)
- [reportError](accelerate/sparsecgoptions/reporterror.md)
- [reportStatus](accelerate/sparsecgoptions/reportstatus.md)