# numeric¶

This module provides math and linear algebra utils that relies on [Eigen] library. Eigen is a C++ template library for linear algebra.

Basic idea is to provide to openMVG :

- a high level memory container for matrices and vectors,
- an easy matrices and vectors manipulation,
- a collection of numeric solvers and related algorithms.

## Vector, Matrix containers¶

OpenMVG redefines some Eigen basis type (points, vectors, matrices) for code consitency and clarity:

`Vec2`

a single 2d point stored as a column matrix (x,y),`Vec3`

a single 3d point stored as a column matrix (x,y,z),`Vec2f, Vec3f`

float version.

`Vec`

a vector of value (double precision),`Vecf`

a vector of floating point value,

`Mat`

the generic matrix container,`Mat2X`

a collection of 2d points stored by column,`Mat3X`

a collection of 3d points stored as column.

Note: Default memory alignment is column major.

```
// Create a set of 2D points store as column
Mat2X A(2, 5);
A << 1, 2, 3, 4, 5,
6, 7, 8, 9, 10;
A.col(); // return a column vector : (1,6)^T
A.row(); // return a row vector : (1,2,3,4,5)
```

## Linear algebra¶

- SVD/QR/LU decomposition.

### To know more¶

Please visit: http://eigen.tuxfamily.org/dox/group__QuickRefPage.html