Enable large arrays: Build octave such that it can use arrays larger than 2Gb.: Difference between revisions
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(Take example from Manual, previous one actually works. Minor formatting improvements.) |
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<pre> | <pre> | ||
>> a = zeros (1024*1024*1024*3, 1, 'int8'); | |||
error: memory | error: out of memory or dimension too large for Octave's index type | ||
</pre> | </pre> | ||
You will obtain this error even if your system has enough RAM to create this array (4 GB in the above case). | You will obtain this error even if your system has enough RAM to create this array (4 GB in the above case). | ||
To use arrays with more than (approximately) 2 | To use arrays with more than (approximately) <math>2^{31}</math> elements, Octave has to be configured with the option <code>--enable-64</code>. This option is experimental and you are (as always) encouraged to submit bug reports if you find a problem. | ||
With this option, Octave will use internally 64-bit integers for array dimensions and indexing. However, '''all numerical libraries''' used by Octave will need to use also 64-bit integers for array dimensions and indexing, and in most cases they need to be compiled from source. | With this option, Octave will use internally 64-bit integers for array dimensions and indexing. However, '''all numerical libraries''' used by Octave will need to use also 64-bit integers for array dimensions and indexing, and in most cases they need to be compiled from source. | ||
Revision as of 11:10, 15 August 2016
Note: the following only applies to systems that have 64-bit pointers (64bit architecture)
By default, the size of a single Octave array cannot exceed 2 GB of memory. Trying to create one will produce the following error:
>> a = zeros (1024*1024*1024*3, 1, 'int8'); error: out of memory or dimension too large for Octave's index type
You will obtain this error even if your system has enough RAM to create this array (4 GB in the above case).
To use arrays with more than (approximately) elements, Octave has to be configured with the option --enable-64. This option is experimental and you are (as always) encouraged to submit bug reports if you find a problem.
With this option, Octave will use internally 64-bit integers for array dimensions and indexing. However, all numerical libraries used by Octave will need to use also 64-bit integers for array dimensions and indexing, and in most cases they need to be compiled from source.
For details about how to compile these libraries please read the GNU Octave manual, or alternatively you can use MXE (M Cross Environment) which takes care of the different packages automatically.