Last modified: 2014-11-18 18:06:31 UTC
The first expression in the following paragraph: Die beiden letzten Ausdrücke für <math>x_{1}^{*}</math> und <math>x_{2}^{*}</math> sind nichts anderes als die jeweiligen ''marshallschen Nachfragefunktionen nach Gut 1 bzw. Gut 2.'' is not rendered properly in MathML mode (no problems with MathJax and PNG), resulting instead in the following error message: Fehler beim Parsen (MathML mit SVG- oder PNG-Rückgriff (empfohlen für moderne Browser und Barrierefreiheitswerkzeuge): Ungültige Antwort („<p>Fehler beim Abruf der URL: Empty reply from server </p>“) von Server „http://mathoid.svc.eqiad.wmnet:10042“:): x_{1}^{*} (From <https://de.wikipedia.org/w/index.php?title=Marshallsche_Nachfragefunktion&oldid=134992435#Beispiel_im_Zwei-G.C3.BCter-Fall>)
I've enabled "MathML mit SVG- oder PNG-Rückgriff" on https://de.wikipedia.org/wiki/Spezial:Einstellungen#mw-prefsection-rendering and can confirm this on https://de.wikipedia.org/w/index.php?title=Marshallsche_Nachfragefunktion&oldid=134992435#Beispiel_im_Zwei-G.C3.BCter-Fall Slightly confused that passing uselang=en in https://de.wikipedia.org/w/index.php?title=Marshallsche_Nachfragefunktion&uselang=en&oldid=134992435#Beispiel_im_Zwei-G.C3.BCter-Fall does not expose the problem.
This looks like a math caching problem to me, as purging that page with ?action=purge&mathpurge=true clears it. (The mathpurge=true bit is currently necessary as the math extension doesn't seem to properly get access to the action parameter; hopefully that can be dropped soon.) The Math extension stores rendered math in the database. I think it should not do this if there was a (temporary) error from the backend server. I'm re-titling this bug to mention both issues.
*** Bug 72536 has been marked as a duplicate of this bug. ***
I saw the same issue again on https://de.wikipedia.org/wiki/Potenzmengenkonstruktion#Automat_zum_regul.C3.A4ren_Ausdruck_.0A.0A_.0A_.28.0A_a.0A_.0A_.7C.0A_.0A_b.0A_.29.0A_.0A_.0A_.0A_.E2.88.97.0A_.0A_a.0A_b.0A_a (first cell in second table) and ?action=purge&mathpurge=true indeed fixed it.
If there is an error on the page nothing should be stored in the database. So I would be surprised if normal &acition=purge would not be sufficient in this situation. Quite a few people tried to implement the access to the purge parameter. All failed. So I think this should be a bug on it's own.
See MathRenderer.php l 520 ff // TODO: Figure out if ?action=purge // $action = $request->getText('action'); //always returns '' // until this issue is resolved we use ?mathpurge=true instead
