It would be very grad for me to be told whether Astahost's PHP mode is safe mode or not.
I would like to run latex and so on through PHP exec command.
But if the PHP mode is safe mode, I will not be able to run them well.

Not an answer, but there is a Latex alternative which is a CGI script - it's called Mimetex. Not as good as Latex, though, but I've never had the need for anything better

Thank you for your reply.
But I am sorry that I have already known mimetex.

I am worried that mimetex does not store the images, so the cgi must be called whenever the formulae will be written and it will take much time.(I plan to use more than 100 formulae a page).
If I can use the texvc, the images are stored in the homepage so it will shorten the time.

Astahost is running PHP Version 5.2.5 on Apache webserver and in php.ini the setting safe_mode is Off, turning it on isn't really good, unless you have a crappy server, for example an old server, which can be hacked if safe mode is off.