---
title: SparseConjugateGradient()
framework: accelerate
role: symbol
role_heading: Function
path: accelerate/sparseconjugategradient()
---

# SparseConjugateGradient()

Returns a conjugate gradient (CG) method.

## Declaration

```swift
func SparseConjugateGradient() -> SparseIterativeMethod
```

## Return Value

Return Value A SparseIterativeMethod structure that represents a default conjugate gradient method.

## Discussion

Discussion 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(_:). For rectangular or singular systems, use SparseLSMR(_:).

## See Also

### Sparse Iterative Methods for Symmetric Positive-Definite Coefficient Matrices

- [SparseConjugateGradient(_:)](accelerate/sparseconjugategradient(_:).md)
- [SparseCGOptions](accelerate/sparsecgoptions.md)