SparseMultiplyAdd(_:_:_:)
Performs the multiply operation Y += AX on a sparse matrix of single-precision, floating-point values.
Declaration
func SparseMultiplyAdd(_ A: SparseMatrix_Float, _ X: DenseMatrix_Float, _ Y: DenseMatrix_Float)Parameters
- A:
The sparse matrix A in Y += AX.
- X:
The dense matrix X in Y += AX.
- Y:
The dense matrix Y in Y += AX.
Discussion
Use this function to multiply a sparse matrix by a dense matrix and accumulate the result. The following equation is an example of a matrix-matrix multiplication where the first matrix is sparse:
[Image]
Call SparseMultiplyAdd(_:_:_:_:) to calculate the result.
let rowCount = Int32(4)
let columnCount = Int32(4)
let blockCount = 4
let blockSize = UInt8(1)
let rowIndices: [Int32] = [0, 3, 0, 3]
let columnIndices: [Int32] = [0, 0, 3, 3]
let data: [Float] = [1.0, 4.0, 13.0, 16.0]
/// The _A_ in _Y+=AX_.
let A = SparseConvertFromCoordinate(rowCount, columnCount,
blockCount, blockSize,
SparseAttributes_t(),
rowIndices, columnIndices,
data)
defer {
SparseCleanup(A)
}
/// The values for _X_ in _Y+=AX_.
var xValues: [Float] = [10.0, -1.0, -1.0, 10.0,
100.0, -1.0, -1.0, 100.0]
/// The values for _Y_ in _Y+=AX_.
var yValues = [Float](repeating: 1,
count: xValues.count)
yValues.withUnsafeMutableBufferPointer { yValuesPtr in
xValues.withUnsafeMutableBufferPointer { denseMatrixPtr in
/// The _X_ in _Y+=AX_.
let X = DenseMatrix_Float(rowCount: 4,
columnCount: 2,
columnStride: 4,
attributes: SparseAttributes_t(),
data: denseMatrixPtr.baseAddress!)
/// The _Y_ in _Y+=AX_.
let Y = DenseMatrix_Float(rowCount: 4,
columnCount: 2,
columnStride: 4,
attributes: SparseAttributes_t(),
data: yValuesPtr.baseAddress!)
SparseMultiplyAdd(A, X, Y)
}
}
// On return, `yValues` contains:
// `[ 141.0, 1.0, 1.0, 201.0,
// 1401.0, 1.0, 1.0, 2001.0]`