Fix explanation of LIst of List sparse matrix
Fix explanation of LIst of List sparse matrix

Thanks to CJ Carey for catching the mistake.

Sparse was introduced to SciPy in this commit:

https://github.com/scipy/scipy-svn/commit/b3827deddd0c1a25986c802b91a4f7d359830ebc

A later update included a list of formats:

https://github.com/scipy/scipy-svn/commit/39730dc5482dad6f92dc8751e2048c0f27b64580

In both these patches the phrase "linked list matrix" is used, but I
believe erroneously. The LIst of List format uses the following representation:

```
In [1]: import scipy.sparse

In [2]: X = scipy.sparse.lil_matrix([[0,0,0,0],[0,1,0,0],[0,0,
   ...: 0,0]])

In [3]: X.data
Out[3]: array([list([]), list([1]), list([])], dtype=object)
```

The intent is to have direct access to any row. This can be achieved with a list of lists, but not with a linked list representation.

andyfaff/scipy,WarrenWeckesser/scipy,scipy/scipy,ilayn/scipy,scipy/scipy,endolith/scipy,anntzer/scipy,mdhaber/scipy,WarrenWeckesser/scipy,Stefan-Endres/scipy,endolith/scipy,scipy/scipy,andyfaff/scipy,WarrenWeckesser/scipy,ilayn/scipy,ilayn/scipy,andyfaff/scipy,anntzer/scipy,anntzer/scipy,scipy/scipy,andyfaff/scipy,ilayn/scipy,Stefan-Endres/scipy,mdhaber/scipy,ilayn/scipy,anntzer/scipy,endolith/scipy,endolith/scipy,Stefan-Endres/scipy,endolith/scipy,ilayn/scipy,endolith/scipy,mdhaber/scipy,scipy/scipy,andyfaff/scipy,WarrenWeckesser/scipy,mdhaber/scipy,anntzer/scipy,Stefan-Endres/scipy,anntzer/scipy,Stefan-Endres/scipy,scipy/scipy,Stefan-Endres/scipy,WarrenWeckesser/scipy,WarrenWeckesser/scipy,andyfaff/scipy,mdhaber/scipy,mdhaber/scipy