Thank you all guys, To Aditya: Clearly I over-emphasized the randomness. Actually, what I meant is a little more complex: identical objects on random coordinates and they don't intersect with each other. We can rotate them but we can't re-size them and scale them. Your code is very interesting. I'll see what I can do now. Thank you again. -- Best Regards Chen ---------------------------------------------------------------- Zhi-chu Chen | Shanghai Synchrotron Radiation Facility No. 2019 | Jialuo Rd. | Jiading | Shanghai | P.R. China tel: 086 21 5955 3405 | zhichu.chen.googlepages.com | www.sinap.ac.cn ----------------------------------------------------------------