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# SparseOpaquePreconditioner_Double

A structure that represents a double-precision preconditioner.

```
struct SparseOpaquePreconditioner_Double
```

## Topics

### Creating a Preconditioner

[`init(type:mem:apply:)`](/documentation/Accelerate/SparseOpaquePreconditioner_Double/init(type:mem:apply:))

Creates a new double-precision preconditioner.

### Inspecting Preconditioner Properties

[`apply`](/documentation/Accelerate/SparseOpaquePreconditioner_Double/apply)

A function that calculates *Y = PX*, where *P* is the preconditioner.

[`mem`](/documentation/Accelerate/SparseOpaquePreconditioner_Double/mem)

The unaltered memory pointer that passes as the first parameter of the apply function.

[`type`](/documentation/Accelerate/SparseOpaquePreconditioner_Double/type)

The preconditioner type.


---

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