Matrex (http://matrex.sourceforge.net/) is a spreadsheet equivalent application that calculates formulas with matrices parameters, not cells. Matrex has charts and presentations (spreadsheets) and is stable and multithreaded. The 12th of january we released MatrexR, that allows to have Matrex as front end of R for matrices calculations. You can download both Matrex and MatrexR from https://sourceforge.net/projects/matrex/.