Ceyhun Can Ülker created MAHOUT-1146:
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Summary: Cardinality exception bug in 'cross' method of
AbstractVector class.
Key: MAHOUT-1146
URL: https://issues.apache.org/jira/browse/MAHOUT-1146
Project: Mahout
Issue Type: Bug
Components: Math
Affects Versions: 0.8
Environment: Ubuntu 12.10 64-bit
Reporter: Ceyhun Can Ülker
Priority: Critical
This bug is probably about the viewColumn method, or matrixLike method or
MatrixVectorView constructor, I didn't really looked into it. But it is easy to
reproduce.
I have a dense matrix U of size 10x670. When I try to do this I get a
cardinality exception, which doesn't make sense:
Vector uI = U.viewColumn(i);
Matrix outerProduct = uI.cross(uI);
Exception is thrown from AbstractMatrix class' cross method, when a row is
tried to be assigned in the result matrix.
public Matrix cross(Vector other) {
Matrix result = matrixLike(size, other.size());
for (int row = 0; row < size; row++) {
result.assignRow(row, other.times(getQuick(row)));
}
return result;
}
The problem here is matrixLike method does not return a 10x10 matrix as it
should, instead it returns 1x1 matrix.
Hope this helps.
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