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# atol

The absolute tolerance (default test) or *A* tolerance (Fong-Saunders test).

```
var atol: Double
```

## Discussion

In the Fong and Saunders case, this value holds an estimate of the relative error in the data defining the matrix *A*. For example, if *A* is accurate to about six digits, set [`atol`](/documentation/Accelerate/SparseLSMROptions/atol) `= 1.0e-6`.

---

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