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https://github.com/daniyal1249/ablina

A Python package for abstract linear algebra
https://github.com/daniyal1249/ablina

computer-algebra linear-algebra manim math python sympy vector-space

Last synced: 5 months ago
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A Python package for abstract linear algebra

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ablina

## Documentation

https://ablina.readthedocs.io/en/latest

## Installation

Ablina can be installed using pip:

pip install ablina

or by directly cloning the git repository:

git clone https://github.com/daniyal1249/ablina.git

and running the following in the cloned repo:

pip install .

## Overview

```python
>>> from ablina import *
```

### Define a Vector Space

To define a subspace of $ℝ^n$ or $ℂ^n$, use ``fn``

```python
>>> V = fn("V", R, 3)
>>> print(V.info())
```

V (Subspace of R^3)
-------------------
Field R
Identity [0, 0, 0]
Basis [[1, 0, 0], [0, 1, 0], [0, 0, 1]]
Dimension 3
Vector [c0, c1, c2]

You can provide a list of constraints

```python
>>> U = fn("U", R, 3, constraints=["v0 == 0", "2*v1 == v2"])
>>> print(U.info())
```

U (Subspace of R^3)
-------------------
Field R
Identity [0, 0, 0]
Basis [[0, 1, 2]]
Dimension 1
Vector [0, c0, 2*c0]

Or specify a basis

```python
>>> W = fn("W", R, 3, basis=[[1, 0, 0], [0, 1, 0]])
>>> print(W.info())
```

W (Subspace of R^3)
-------------------
Field R
Identity [0, 0, 0]
Basis [[1, 0, 0], [0, 1, 0]]
Dimension 2
Vector [c0, c1, 0]

### Operations with Vectors

Check whether a vector is an element of a vector space

```python
>>> [1, 2, 0] in W
```

True

```python
>>> [1, 2, 1] in W
```

False

Generate a random vector from a vector space

```python
>>> U.vector()
```

[0, 2, 4]

```python
>>> U.vector(arbitrary=True)
```

[0, c0, 2*c0]

Find the coordinate vector representation of a vector

```python
>>> W.to_coordinate([1, 2, 0])
```

[1, 2]

```python
>>> W.from_coordinate([1, 2])
```

[1, 2, 0]

```python
>>> W.to_coordinate([1, 2, 0], basis=[[1, 1, 0], [1, -1, 0]])
```

[3/2, -1/2]

Check whether a list of vectors is linearly independent

```python
>>> V.is_independent([1, 1, 0], [1, 0, 0])
```

True

```python
>>> V.is_independent([1, 2, 3], [2, 4, 6])
```

False

### Operations on Vector Spaces

Check for equality of two vector spaces

```python
>>> U == W
```

False

Check whether a vector space is a subspace of another

```python
>>> V.is_subspace(U)
```

True

```python
>>> U.is_subspace(V)
```

False

Take the sum of two vector spaces

```python
>>> X = U.sum(W)
>>> print(X.info())
```

U + W (Subspace of R^3)
-----------------------
Field R
Identity [0, 0, 0]
Basis [[1, 0, 0], [0, 1, 0], [0, 0, 1]]
Dimension 3
Vector [c0, c1, c2]

Take the intersection of two vector spaces

```python
>>> X = U.intersection(W)
>>> print(X.info())
```

U ∩ W (Subspace of R^3)
-----------------------
Field R
Identity [0, 0, 0]
Basis []
Dimension 0
Vector [0, 0, 0]

Take the quotient of two vector spaces

```python
>>> X = V.quotient(U)
>>> print(X.info())
```

V / U (Subspace of R^3 / U)
---------------------------
Field R
Identity U + [0, 0, 0]
Basis [U + [1, 0, 0], U + [0, 1, -1/2]]
Dimension 2
Vector U + [c0, c1, -c1/2]

Take the span of a list of vectors

```python
>>> S = V.span("S", [1, 2, 3], [4, 5, 6])
>>> print(S.info())
```

S (Subspace of R^3)
-------------------
Field R
Identity [0, 0, 0]
Basis [[1, 0, -1], [0, 1, 2]]
Dimension 2
Vector [c0, c1, -c0 + 2*c1]

### Define a Linear Map

```python
>>> def mapping(vec):
>>> return [vec[0], vec[1], 0]
>>>
>>> T = LinearMap("T", domain=V, codomain=W, mapping=mapping)
>>> print(T.info())
```

T : V → W
---------
Field R
Rank 2
Nullity 1
Injective? False
Surjective? True
Bijective? False
Matrix [[1, 0, 0], [0, 1, 0]]

```python
>>> T([0, 0, 0])
```

[0, 0, 0]

```python
>>> T([1, 2, 3])
```

[1, 2, 0]

### Operations with Linear Maps

Find the image of a linear map

```python
>>> im = T.image()
>>> print(im.info())
```

im(T) (Subspace of R^3)
-----------------------
Field R
Identity [0, 0, 0]
Basis [[1, 0, 0], [0, 1, 0]]
Dimension 2
Vector [c0, c1, 0]

Find the kernel of a linear map

```python
>>> ker = T.kernel()
>>> print(ker.info())
```

ker(T) (Subspace of R^3)
------------------------
Field R
Identity [0, 0, 0]
Basis [[0, 0, 1]]
Dimension 1
Vector [0, 0, c0]

### Define an Inner Product

Here we define the standard dot product

```python
>>> def mapping(vec1, vec2):
>>> return sum(i * j for i, j in zip(vec1, vec2))
>>>
>>> dot = InnerProduct("dot", vectorspace=V, mapping=mapping)
>>> print(dot.info())
```

dot : V × V → R
---------------
Orthonormal Basis [[1, 0, 0], [0, 1, 0], [0, 0, 1]]
Matrix [[1, 0, 0], [0, 1, 0], [0, 0, 1]]

```python
>>> dot([1, 2, 3], [1, 2, 3])
```

14

### Operations with Inner Products

Compute the norm of a vector

```python
>>> dot.norm([1, 2, 3])
```

sqrt(14)

Check whether a list of vectors is pairwise orthogonal

```python
>>> dot.is_orthogonal([1, 2, 3], [4, 5, 6])
```

False

```python
>>> dot.is_orthogonal([0, 0, 0], [1, 2, 3])
```

True

Check whether a list of vectors is orthonormal

```python
>>> dot.is_orthonormal([1, 0, 0], [0, 1, 0], [0, 0, 1])
```

True

Take the orthogonal complement of a vector space

```python
>>> X = dot.ortho_complement(U)
>>> print(X.info())
```

perp(U) (Subspace of R^3)
-------------------------
Field R
Identity [0, 0, 0]
Basis [[1, 0, 0], [0, 1, -1/2]]
Dimension 2
Vector [c0, c1, -c1/2]

### Define a Linear Operator

```python
>>> def mapping(vec):
>>> return [vec[0], 2*vec[1], 3*vec[2]]
>>>
>>> T = LinearOperator("T", vectorspace=V, mapping=mapping)
>>> print(T.info())
```

T : V → V
---------
Field R
Rank 3
Nullity 0
Injective? True
Surjective? True
Bijective? True
Matrix [[1, 0, 0], [0, 2, 0], [0, 0, 3]]

```python
>>> T([1, 1, 1])
```

[1, 2, 3]

### Operations with Linear Operators

Given an inner product, check whether a linear operator

```python
>>> T.is_symmetric(dot)
```

True

```python
>>> T.is_hermitian(dot)
```

True

```python
>>> T.is_orthogonal(dot)
```

False

```python
>>> T.is_unitary(dot)
```

False

```python
>>> T.is_normal(dot)
```

True