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# convergenceTest

The convergence test to use for iterative solve methods.

```
var convergenceTest: SparseLSMRConvergenceTest_t
```

## Discussion

For [`SparseLSMRCTDefault`](/documentation/Accelerate/SparseLSMRCTDefault), iterations stop when:

- *‖ Aᵀ(b-Ax) ‖₂ < ``doc://com.apple.accelerate/documentation/Accelerate/SparseLSMROptions/rtol`` * ‖ Aᵀ(b-Ax_₀) ‖₂ + ``doc://com.apple.accelerate/documentation/Accelerate/SparseLSMROptions/atol``*

For [`SparseLSMRCTFongSaunders`](/documentation/Accelerate/SparseLSMRCTFongSaunders), iterations stop when any of the following occur:

- *‖ b-Ax ‖₂ < ``doc://com.apple.accelerate/documentation/Accelerate/SparseLSMROptions/btol`` * ‖ b ‖₂ + ``doc://com.apple.accelerate/documentation/Accelerate/SparseLSMROptions/atol`` * ‖ A ‖₂ ‖ x ‖₂*    (*‖A‖₂* is an estimate)
- *‖ Aᵀ (b-Ax) ‖₂ < ``doc://com.apple.accelerate/documentation/Accelerate/SparseLSMROptions/atol`` * ‖ A ‖₂ * ‖ A-bx ‖₂*             (*‖A‖₂* is an estimate)
- Estimated condition of *matrix >= ``doc://com.apple.accelerate/documentation/Accelerate/SparseLSMROptions/conditionLimit``*

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