mecej, I will save your post 

mecej, I will save your post  (http://software.intel.com/en-us/comment/reply/394023/1741446?quote=1#com...)  because of it contains very useful comments  " If you want to perform meaningful tests of matrix algebra routines, do not try with garbage matrices or null matrices. It is not that difficult to generate a nonsingular symmetric matrix of size larger than 40 X 40."

this is pretty simple tips, but nevertheless, many users do that. :)