Fatal error: Uncaught Error: Call to undefined function ereg() in /homepages/45/d116745460/htdocs/shelswell.org.uk/wp-content/plugins/wpmathpub/phpmathpublisher/mathpublisher.php:1604 Stack trace: #0 /homepages/45/d116745460/htdocs/shelswell.org.uk/wp-content/plugins/wpmathpub/phpmathpublisher/mathpublisher.php(1625): detectimg('3fdd385e3f876b1...') #1 /homepages/45/d116745460/htdocs/shelswell.org.uk/wp-content/plugins/wpmathpub/phpmathpublisher/mathpublisher.php(1661): mathimage('a_k = ar^{k-1}', '12', 'http://teaching...') #2 /homepages/45/d116745460/htdocs/shelswell.org.uk/wp-content/plugins/wpmathpub/wpmathpub.php(110): mathfilter('<m>a_k = ar^{k-...', '12', 'http://teaching...') #3 [internal function]: wpmathfilter(Array) #4 /homepages/45/d116745460/htdocs/shelswell.org.uk/wp-content/plugins/wpmathpub/wpmathpub.php(124): preg_replace_callback('#\\[pmath(\\s+siz...', 'wpmathfilter', 'A geometric seq...') #5 /homepages/45/d116745460/htdocs/shelswell.org.uk/wp-includes/class-wp-hook.php(286): to_phpmath('A geometric seq in /homepages/45/d116745460/htdocs/shelswell.org.uk/wp-content/plugins/wpmathpub/phpmathpublisher/mathpublisher.php on line 1604