---
title: apply
framework: accelerate
role: symbol
role_heading: Instance Property
path: accelerate/sparseopaquepreconditioner_double/apply
---

# apply

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

## Declaration

```swift
var apply: (UnsafeMutableRawPointer, CBLAS_TRANSPOSE, DenseMatrix_Double, DenseMatrix_Double) -> Void
```

## Discussion

Discussion The function has some approximation to A⁻¹.

## See Also

### Inspecting Preconditioner Properties

- [mem](accelerate/sparseopaquepreconditioner_double/mem.md)
- [type](accelerate/sparseopaquepreconditioner_double/type.md)