pycauset.UnitVector

A storage-less vector representing a standard basis vector \(e_k\) (all zeros except a 1 at index \(k\)). Inherits from VectorBase.

This vector type uses 0 bytes of disk storage. It stores the active index \(k\) in metadata.

Constructor

pycauset.UnitVector(n: int, active_index: int)

• n: The size of the vector.
• active_index: The index where the value is 1. Must be \(0 \le k < n\).

Properties

shape

Returns a tuple representing the dimensions of the vector.

Methods

__getitem__(i: int) -> float

Get the value at index i. Returns 1.0 if i == active_index, else 0.0.

__len__() -> int

Get the size of the vector.

__repr__() -> str

String representation of the vector.

Arithmetic

• UnitVector + UnitVector:
  • If active indices match: Returns a UnitVector (scaled).
  • If active indices differ: Returns a DenseVector (e.g., \(e_1 + e_2\)).
• UnitVector + DenseVector: Returns a DenseVector.