October 14, 2004

Error Reporting

To fix bugs, you need to know about them first. Discovering bugs in itex2MML is particularly tricky, since nobody actually wants to look at the gobbledygook that is its MathML output. If the result renders OK in Mozilla and passes the W3C Validator, one tends to assume that it’s correct. Even when it doesn’t render properly, half the time the problem a bug in Mozilla’s MathML rendering code, rather than a bug in itex2MML.

One of the nifty features of the MathPlayer plugin for IE/6 is that, unlike Mozilla, it does a crude, but effective, form of error-reporting. Whenever it encounters incorrect MathML syntax, it renders it as best it can, but then colours the result red.

It was thus that Grant Focas discovered a bug in itex2MML. A ‘unary’ minus sign was being converted to <mo lspace="thinthinmathspace" rspace="0em">-</mo> instead of the syntactically correct <mo lspace="verythinmathspace" rspace="0em">-</mo>. Many thanks to Grant and to the kind folks at DesignScience for bringing this to my attention.

I’ve fixed the problem in my itex2MML distribution, and anyone using the itexToMML plugin for MovableType, WordPress, B2Evolution, PyBloxsom or ecto should update their itex2MML executable to the latest version.

And I want to put out a request to all of you reading this blog or the String Coffee Table in IE/6+MathPlayer: if you see a snippet of mathematical text rendered in red, please let me know. Similarly, anyone reading in any MathML-enabled browser1, please let me know if some equations don’t seem to render correctly.

1 That’s 40% of you, at last count. It could be 69% if the rest of the IE/6 users would just download the MathPlayer plugin. I think I am going to gently nudge them in that direction. Yep, yet another annoying “nag” popup…

Posted by distler at October 14, 2004 11:03 PM

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Re: Error Reporting

I used to see reddened pieces here and there in formulas when using the MathML plugin to view the String Coffee Table. But since I usually use Mozilla instead, I don’t have a good up-to-date overview. A spot checked turned up one red formula in this comment, one in this.

What I find most annoying when reading the SCT with IE is that it messes up the left side margin of the text in long threads of nested comments.

Posted by: Urs Schreiber on October 15, 2004 4:19 AM | Permalink | PGP Sig | Reply to this

Re: Error Reporting

Then I tried various programs to write the MathML formulae, such as the Formulator (Hermitech), but it has not been possible to include these MathML pieces to blogger.com so far - perhaps the files must be *.xhtml so that MathML inside is tolerated?

Posted by: Lubos Motl on October 16, 2004 9:36 AM | Permalink | Reply to this

Re: Error Reporting

That’s right.

Both MathPlayer for IE/6 and Mozilla will only interpret the embedded MathML when the web page is sent with an “XML MIME type” (usually application/xhtml+xml). You don’t control the MIME type used by Blogger, so you don’t have the option of including MathML on your pages.

You can save a web page with embedded MathML to a file and open the local file in IE/6+MathPlayer. If the page was otherwise a “well-formed” XHTML+MathML document, it will then display correctly.

This “well-formedness” requirement is because XML parsers (as used by MathPlayer and by Mozilla to handle XHTML+MathML documents) are, by design, fault-intolerant. With MovableType or WordPress or PyBloxsom, you can pop open the hood and customize the engine to reliably convert TeX input to well-formed XHTML+MathML output. With Blogger, you can’t.

I wrote a boring series (I,II,III,IV,V) of posts about the steps required to make this blog and the String Coffee Table work in the desired fashion. Without comments or trackbacks, etc., the task is infinitely easier. But without them, blogging is not much fun, is it?

Posted by: Jacques Distler on October 16, 2004 11:13 AM | Permalink | PGP Sig | Reply to this

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