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From "Dusan Ku (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MATH-717) A varied class of Array2DRowRealMatrix is needed to contain float type instead of double.
Date Sun, 11 Dec 2011 22:48:39 GMT

    [ https://issues.apache.org/jira/browse/MATH-717?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13167233#comment-13167233
] 

Dusan Ku commented on MATH-717:
-------------------------------

It is very natural to have very large matrices in mathematical programming. In many of my
experiments, usually linear programming, If you're not sure of the potential problem between
float and double, please run the below samples separately under the following VM option: -Xmx1G

#case 1) for float:
	public static void main(String[] args) {
		float[][] d = new float[15000][15000];
		System.out.println("OK");
	}

#case 2) for double:
	public static void main(String[] args) {
		float[][] d = new float[15000][15000];
		System.out.println("OK");
	}
                
> A varied class of Array2DRowRealMatrix is needed to contain float type instead of double.
> -----------------------------------------------------------------------------------------
>
>                 Key: MATH-717
>                 URL: https://issues.apache.org/jira/browse/MATH-717
>             Project: Commons Math
>          Issue Type: Improvement
>    Affects Versions: 2.2
>         Environment: All
>            Reporter: Dusan Ku
>              Labels: features
>
> The current implementation of Array2DRowRealMatrix takes only double type as its base
element value in the matrix.
> However, the memory size of double is bigger than float, the downside of which makes
the matrix dimension quite limited, compared to float type as its base element type. For small
sized problem, this does not make such a big difference, but for large problems, this limits
the usability of this library quite severely. In my case, I easily hit an error even after
I increase the memory option to 1G. This could have been much more enhanced just by using
'float[][]' instead of the current Array2DRowRealMatrix.
> Therefore, the solution I may suggest is to add another class similar to Array2DRowRealMatrix
containing float type for its matrix variable instead of double. Of course, a better way is
welcome as long as the needs can be fulfilled.

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