how to know when a php library is installed

Hello all: I need to test whether a library is installed with php or not. In this case it's the tidy library I need for a project. After getting a message from the hosting administrator that the tidy library was installed and ready to use I ran a phpinfo() to find out details: There's nothing that looks like tidy in the Configure Command: Configure Command './configure' 'i386-redhat-linux' '--prefix=/usr' '--exec-prefix=/usr' '--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc' '--datadir=/usr/share' '--includedir=/usr/include' '--libdir=/usr/lib' '--libexecdir=/usr/libexec' '--localstatedir=/var' '--sharedstatedir=/usr/com' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--prefix=/usr' '--cache-file=../config.cache' '--with-config-file-path=/etc' '--with-config-file-scan-dir=/etc/php.d' '--enable-force-cgi-redirect' '--disable-debug' '--enable-pic' '--disable-rpath' '--enable-inline-optimization' '--with-bz2' '--with-db3' '--with-curl' '--with-pear' '--with-dom=/usr' '--with-exec-dir=/usr/bin' '--with-freetype-dir=/usr' '--with-png-dir=/usr' '--with-gd' '--enable-gd-native-ttf' '--with-ttf' '--with-gdbm' '--with-gettext' '--with-ncurses' '--with-gmp' '--with-iconv' '--with-jpeg-dir=/usr' '--with-openssl' '--with-png' '--with-pspell' '--with-regex=system' '--with-xml' '--with-expat-dir=/usr' '--with-pcre=/usr' '--with-zlib' '--with-layout=GNU' '--enable-bcmath' '--enable-exif' '--enable-ftp' '--enable-magic-quotes' '--enable-safe-mode' '--enable-sockets' '--enable-sysvsem' '--enable-sysvshm' '--enable-discard-path' '--enable-track-vars' '--enable-trans-sid' '--enable-yp' '--enable-wddx' '--without-oci8' '--with-pear=/usr/share/pear' '--with-imap=shared' '--with-imap-ssl' '--with-kerberos' '--with-ldap=shared' '--with-mysql=shared,/usr' '--with-pgsql' '--with-snmp=shared,/usr' '--with-snmp=shared' '--enable-ucd-snmp-hack' '--with-unixODBC=shared' '--enable-memory-limit' '--enable-bcmath' '--enable-shmop' '--enable-versioning' '--enable-calendar' '--enable-dbx' '--enable-dio' '--enable-mcal' '--enable-mbstring' '--enable-mbstr-enc-trans' '--enable-mbregex' '--enable-cgi' However there is a section in the phpinfo output that shows: tidy Tidy support enabled libTidy Build Date 1 July 2005 Directive Local Value Master Value tidy.default_config no value no value Tidy Configuration Directive Value indent-spaces 0 .... I've tried to run this php code to call tidy functions: <? $html = ' <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head><title>title</title></head> <body> <p>paragraph <bt /> text</p> </body></html> '; $tidy = new tidy; $tidy->parseString($html); $tidy->CleanRepair(); if ($tidy->errorBuffer) { echo "The following errors were detected:\n"; echo $tidy->errorBuffer; } ?> And always get the error cannot instantiate nonexistent class. Any input, comments are more than welcome, Lizet