Thanks Prof. Ripley's response! However, I have to apologize to Prof. Ripley & all R-friends: the problem (after I re-tried several times) is neither on R nor on Ghostscript. It is on the DVI-preview program I used: YAP, it causes color yellow to purple, blue to green, red to blue, ... on the included postscript files. I am very sorry to bother everyone with this! Best regards, Joseph Lu P.S. Thanks Prof. Ripley again on advising updating my R to new version. -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._