LSA algorithm

Hi,

I want to use LSA algorithm (Latent Semantic Indexing) on my high dimensional text data as a Dimensionality reduction phase. RM has an LSA operator (originally from weka) which is named as "W_LatetntSemanticIndexing". but it is located in "Attribute Weighting" group. Now, I want to know the difference of this operator with the standard LSA algorithm. I mean is it possible for me to use this operator as an standard LSA operator? If the answer is positive (I wish...), please explain how should I use "W_LatetntSemanticIndexing" as a standard LSA algorithm for reducing the number of my features...


Any idea, will be greatly appreciated.