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# SparseCGOptions

Options for creating a conjugate gradient (CG) method.

```
struct SparseCGOptions
```

## Overview

Use CG to solve *Ax = b* when *A* is symmetric positive-definite. The method may break down or fail to converge if *A* isn’t positive-definite.

For square, full-rank, unsymmetric or indefinite equations, use [`SparseGMRES(_:)`](/documentation/Accelerate/SparseGMRES(_:)). For rectangular or singular systems, use [`SparseLSMR(_:)`](/documentation/Accelerate/SparseLSMR(_:)).

## Topics

### Initializers

[`init()`](/documentation/Accelerate/SparseCGOptions/init())

Returns a new CG options structure.

[`init(reportError:maxIterations:atol:rtol:reportStatus:)`](/documentation/Accelerate/SparseCGOptions/init(reportError:maxIterations:atol:rtol:reportStatus:))

Returns a new CG options structure using the specified parameters.

### Inspecting CG Options

[`atol`](/documentation/Accelerate/SparseCGOptions/atol)

The absolute convergence tolerance.

[`maxIterations`](/documentation/Accelerate/SparseCGOptions/maxIterations)

The maximum number of iterations to perform.

[`reportError`](/documentation/Accelerate/SparseCGOptions/reportError)

An optional error-reporting routine.

[`reportStatus`](/documentation/Accelerate/SparseCGOptions/reportStatus)

The function to report status.

[`rtol`](/documentation/Accelerate/SparseCGOptions/rtol)

The relative convergence tolerance.


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