# hama-dev mailing list archives

##### Site index · List index
Message view
Top
From "Edward J. Yoon (JIRA)" <j...@apache.org>
Subject [jira] Created: (HAMA-190) Bug in Matrix-Vector multiplication
Date Thu, 10 Sep 2009 01:39:57 GMT
```Bug in Matrix-Vector multiplication
-----------------------------------

Key: HAMA-190
URL: https://issues.apache.org/jira/browse/HAMA-190
Project: Hama
Issue Type: Bug
Components: implementation
Affects Versions: 0.1.0
Reporter: Edward J. Yoon
Assignee: Edward J. Yoon
Fix For: 0.1.0

Hi again,

Since I've more complex operations, (such as multiply, inverse, load...) I decided coding

I've wrote simple example to multiple 2 matrixes, and got incorrect results, can you let me
know if I've some mistake, or it's well known bug.

A =     1,2
3,4

B =     1
2

The result should be (C = A * B):
C =     5
11

But I got incorrect results from the example below:
1.0,2.0
3.0,6.0

The code:

public static void main(String[] args) throws IOException {

conf.set("hbase.rootdir", "hdfs://lb-emu-2:54310/hbase");
conf.set("hbase.master", "lb-emu-2:60000");
conf.set("mapred.jar", "/app/installs/hama/hama-0.1.0-dev.jar");

DenseMatrix a = new DenseMatrix(conf, "A", true);

a.setDimension(2, 2);
a.set(0, 0, 1);
a.set(0, 1, 2);
a.set(1, 0, 3);
a.set(1, 1, 4);

DenseMatrix b = new DenseMatrix(conf, "B", true);

b.setDimension(2, 1);
b.set(0, 0, 1);
b.set(0, 1, 2);

DenseMatrix c = a.mult(b);

for (int i = 0; i < c.getRows(); i++) {
for (int j = 0; j < c.getColumns(); j++) {
System.out.print(c.get(i, j) + " ");
}
System.out.println("");
}
}

Thanks again,
Nir.

--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.

```
Mime
View raw message