com.eignex.koblas/StridedVector

StridedVector

class StridedVector @JvmOverloads constructor(val values: DoubleArray, val offset: Int, val size: Int, val stride: Int = 1) : DenseVector(source)

A mutable live window of size entries in values, starting at offset and separated by stride.

The stepped shape of DenseVector: every entry is stored, so a vendor addresses it as a pointer and an increment exactly as it does a contiguous one. Negative stride is supported when both ends remain in the buffer. This shape always borrows values rather than copying it, so mutations through it or through any other reference to the array are visible to each other.

Constructors

StridedVector

@JvmOverloads

constructor(values: DoubleArray, offset: Int, size: Int, stride: Int = 1)(source)

Properties

offset

open override val offset: Int(source)

First physical entry of this vector within values.

size

open override val size: Int(source)

Number of entries, counting the unstored zeros of a sparse vector.

stride

open override val stride: Int(source)

Physical distance between adjacent entries, which may be negative but is never zero.

values

open override val values: DoubleArray(source)

Borrowed or owned backing array.

Functions

get

open operator override fun get(i: Int): Double(source)

The entry at index (i). Throws IndexOutOfBoundsException outside 0 until size, whatever the storage.

set

open operator override fun set(i: Int, v: Double)(source)

Writes (v) at index (i).

toDoubleArray

open override fun toDoubleArray(): DoubleArray(source)

Materialise into a fresh dense DoubleArray, independent of the internal storage.

toString

open override fun toString(): String(source)

asum

fun Vector.asum(): Double

Sum of absolute values (BLAS dasum). Sparse vectors sum over stored entries only.

asView

fun DenseVector.asView(): StridedVector

A borrowed view over this whole vector, keeping whatever origin and spacing it already has.

axpy

fun DenseVector.axpy(alpha: Double, x: Vector)

y = y + alpha * x. A sparse x touches only the positions it stores. A dense x with an identical mapping is read directly; other dense overlaps, or sparse values sharing the destination buffer, are snapshotted before writing. Custom Vector implementations are also snapshotted, since their backing storage is opaque.

dot

infix fun Vector.dot(other: Vector): Double

aT * b. Sparse operands walk their stored entries only.

forEachStored

inline fun Vector.forEachStored(block: (i: Int, v: Double) -> Unit)

Visit each stored entry as (index, value), in ascending index order for any storage. A SparseVector may present numerical zeros as stored, and any other Vector has every index visited.

iamax

fun Vector.iamax(): Int

Zero-based logical index of the maximum absolute value (BLAS idamax), or -1 when empty. Dense vectors use DenseVectorKernels.iamax; sparse vectors visit only their stored entries. All-zero nonempty inputs return 0, as do sparse inputs whose maximum is an implicit zero. Strided views report their logical index rather than a backing-array offset.

minus