[R] how to do calculations in data matrices?

[Zoppoli, Gabriele (NIH/NCI) [G]]

Please give me just a reference where I can find something useful. 

In summary, I need to :

- find the median of each row of a matrix
- create a new matrix with each value in the first matrix divided by the median of its row
- if a value "a" in the second matrix is < 1, I need to substitute it with 1/a

I know that for some of you it must be overeasy, but I swear I googled for two hours with keywords "operations", "calculations", "data matrices", "data tables", and "CRAN", and I didn't find anything useful. 

Thank you all


Gabriele Zoppoli, MD
Ph.D. Fellow, Experimental and Clinical Oncology and Hematology, University of Genova, Genova, Italy
Guest Researcher, LMP, NCI, NIH, Bethesda MD

Work: 301-451-8575
Mobile: 301-204-5642
Email: zoppolig at mail.nih.gov