[R] about vsn

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Hi all: Are thare anyones that use vsn?Some questions need your help.Thanks a lot 1.If e1(raw data) contain 2419 genes, after e2<-vsn(e1),e2 contains 2419*2 genes. Why does it happen? 
2.How the ¡°calibrated and glog-transformation¡± is perform. In other words, what¡¯s the calculation method behind it? Thanks !