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Re: 0-1 sparse representations?
From: |
c. |
Subject: |
Re: 0-1 sparse representations? |
Date: |
Sun, 20 Nov 2011 08:57:07 +0100 |
On 19 Nov 2011, at 22:33, Jordi Gutiérrez Hermoso wrote:
> No. Sparse matrices must be of float types.
Do they?
---------------------------------------------------------------
>> b = sparse ([1 2 3]', [1 3 3]', true(3, 1))
b =
Compressed Column Sparse (rows = 3, cols = 3, nnz = 3 [33%])
(1, 1) -> 1
(2, 3) -> 1
(3, 3) -> 1
>> whos b
Variables in the current scope:
Attr Name Size Bytes Class
==== ==== ==== ===== =====
b 3x3 31 logical
Total is 3 elements using 31 bytes
---------------------------------------------------------------
isn't this a sparse matrix of logicals?
and it does seem to use less memory than a matrix of doubles:
---------------------------------------------------------------
>> b = sparse ([1 2 3]', [1 3 3]', ones(3, 1))
b =
Compressed Column Sparse (rows = 3, cols = 3, nnz = 3 [33%])
(1, 1) -> 1
(2, 3) -> 1
(3, 3) -> 1
>> whos b
Variables in the current scope:
Attr Name Size Bytes Class
==== ==== ==== ===== =====
b 3x3 52 double
Total is 3 elements using 52 bytes
---------------------------------------------------------------
c.