I've just solved my problem and using matlab in LAS

[Chi Ding <chi@xxxxxxxxx>]

Hi there
      I made a stupid mistake. I passed $self->{output_file} into 
matlab code
as the file name to be created. It turned  out  the $self->{output_file} 
contains a string like
output/c22c3b6fb05e6fb3ba612bd6e805f8a1.gif
      And the statment in my matlab code  to write the picture is below
eval(['print -dpng /home/local/las/server/output/' filename])
      It already contains "output/".  But there is no 
server/output/output/ directory!
      That's the reason I failed! How stupid I am. :-) I guess that's 
because last friday I was
too exhausted to carefully debug my problem.
      Now it's working . I can see the picture rendered by matlab using 
netscape 7.0
      Thanks for your help, guys.
      Cheers, Ding