The ISP for mathTeX's public web service no longer permits "dreamhost" subdomains. That means your <img> tags of the form
<img_src="http://www.forkosh.dreamhost.com/mathtex.cgi?c=\sqrt{a^2+b^2}">
will not work after November 30, 2011. Change them all to
<img_src="http://www.forkosh.com/mathtex.cgi?c=\sqrt{a^2+b^2}">
That is, just remove the "dreamhost." from all tags. That works right now. To repeat, the address of the public mathTeX server is now
http://www.forkosh.com/mathtex.cgi
so write tags of the form
<img_src="http://www.forkosh.com/mathtex.cgi?c=\sqrt{a^2+b^2}">
to access it. Thanks, John Forkosh
http://wordpress.org/extend/plugins/youngwhans-simple-latex/
