Hi, everyone, I assumed that C/C++ code would be faster than Matlab. But to my surprise, I found that svd routine in matlab is much faster than the one in vxl. I tried it on a 660*660 matrix, it took matlab <5 seconds. While in using vnl_svd, it took about more than 20 seconds. Does someone has an idea about this? Thanks in advance! -- Best wishes, Bing Jian bjian at cise . ufl . edu