---
title: "sparse_matrix_block_create_double(_:_:_:_:)"
framework: accelerate
role: symbol
role_heading: Function
path: "accelerate/sparse_matrix_block_create_double(_:_:_:_:)"
---

# sparse_matrix_block_create_double(_:_:_:_:)

Returns a double-precision sparse matrix object that is stored in block-entry format with a fixed block size.

## Declaration

```swift
func sparse_matrix_block_create_double(_ Mb: sparse_dimension, _ Nb: sparse_dimension, _ k: sparse_dimension, _ l: sparse_dimension) -> sparse_matrix_double!
```

## Parameters

- `Mb`: The number of rows in terms of blocks of the matrix. There are a total of Mb * k rows in the matrix. Must be greater than 0.
- `Nb`: The number of columns in terms of blocks of the matrix. There are a total of Nb * l columns in the matrix. Must be greater than 0.
- `k`: The row dimension of a block in the sparse matrix. Must be greater than 0.
- `l`: The column dimension of a block in the sparse matrix. Must be greater than 0.

## Return Value

Return Value A matrix object that is ready for receiving entries.  If an error occurs, nil is returned.

## Discussion

Discussion Create a sparse matrix object that is stored in block-entry format and is ready to receive values from the various block insert routines.  Blocks are are of fixed dimensions k * l.  Block-entry format means blocks of dense regions will be stored at block indices i,j.  For point wise format use non block version of create. See the various insert routines for details on inserting values into this matrix object. important: Apple provides the BLAS and LAPACK libraries under the Accelerate framework to be in line with LAPACK 3.9.1. Starting with iOS 26, iPadOS 26, macOS 26, tvOS 26, visionOS 26, and watchOS 26, the libraries are in line with LAPACK 3.12.0. These new interfaces provide additional functionality, as well as a new ILP64 interface. To use the new interfaces, define ACCELERATE_NEW_LAPACK before including the Accelerate or vecLib headers. For ILP64 interfaces, also define ACCELERATE_LAPACK_ILP64. For Swift projects, specify ACCELERATE_NEW_LAPACK=1 and ACCELERATE_LAPACK_ILP64=1 as preprocessor macros in Xcode build settings under Apple Clang - Preprocessing > Preprocessor Macros.

## See Also

### Matrix creation and population

- [sparse_matrix_block_create_float(_:_:_:_:)](accelerate/sparse_matrix_block_create_float(_:_:_:_:).md)
- [sparse_matrix_variable_block_create_double(_:_:_:_:)](accelerate/sparse_matrix_variable_block_create_double(_:_:_:_:).md)
- [sparse_matrix_variable_block_create_float(_:_:_:_:)](accelerate/sparse_matrix_variable_block_create_float(_:_:_:_:).md)
- [sparse_insert_block_double(_:_:_:_:_:_:)](accelerate/sparse_insert_block_double(_:_:_:_:_:_:).md)
- [sparse_insert_block_float(_:_:_:_:_:_:)](accelerate/sparse_insert_block_float(_:_:_:_:_:_:).md)
- [sparse_matrix_block_create_double_complex(_:_:_:_:)](accelerate/sparse_matrix_block_create_double_complex(_:_:_:_:).md)
- [sparse_matrix_block_create_float_complex(_:_:_:_:)](accelerate/sparse_matrix_block_create_float_complex(_:_:_:_:).md)