Empty Math Zone Place Holders

You type Alt+= or click the Insert ribbon Equation button, and presto! You’ve inserted an empty math zone place holder that states “Type equation here.” in the language you’re using. Then you type a^2+b^2<space> and you see a2+b2, except in better typography. The empty math zone place holder seems simple and intuitive, but behind the scenes a fair amount of software is handling a variety of situations that probably don’t come to mind when you do the things above.

For example, if you cursor away from the math zone, either by using the arrow keys or the mouse, the empty math zone place holder remains; it’s just not selected anymore. If you save the file and reopen it, you’ll see the place holder just where you inserted it. If you select the place holder, possibly with text surrounding it, and copy paste it somewhere else in the document, you’ll see it pasted at the target location.

Furthermore if you return to the place holder, either using the arrow keys or the mouse, the place holder will automatically be reselected. So if you then type something, what you type replaces the place holder. Yet another characteristic: if you type Backspace in a math zone until the last character is deleted, the empty math zone place holder reappears and is selected. Naturally if you type Backspace yet one more time, the place holder is deleted, just as it is if you type the Delete key.

Now what if you type Alt+= immediately before or after an unselected empty math zone place holder? You guessed it! Instead of inserting a new place holder, the current one is reselected. There are other variations that Word 2007 doesn’t get quite right: if you select a bunch of text including one or more empty math zone place holders and then type Alt+=, you’d probably expect the included empty math zone place holders to be deleted, since they’re inside a math zone and nested math zones aren’t permitted. But Word 2007 doesn’t catch this relatively unlikely scenario (it doesn’t crash either, thank goodness!)

The bottom line is that the seemingly simple idea of having a place holder for inserting some math isn’t as straightforward as you might expect.

What do to in the future? The empty math zone place holder is clearly a useful math user interface feature, even if it is tricky to implement correctly. In addition, particularly for educational purposes, one might like to have other place holders within nonempty math zones to ask the user to type, for example, the numerator of a fraction or the integrand of an integral. Such place holders also could be copied and saved to file and reselected by moving the insertion point into them.

Comments (7)

  1. Koby Kahane says:

    There is a very frustrating bug related to math zones and RTL (right-to-left) text in Word 2007 that was disappointingly not fixed in the recently released Office 2007 SP2.

    If a Display equation is inserted when in an Hebrew (and presumably other RTL languages) paragraph, everything seems fine, and the equation even appears as entered in Print Preview. However, when exporting a PDF or simply printing the document, the left edge of the equation is visible at right margin of the page, and the rest of the equation is chopped off and not visible at all. Switching to an English LTR paragraph before pressing Alt-= is a workaround for this issue.

    Math zones in general have poor interaction with RTL. When entering an equation inline inside RTL text, Word really ought to switch the input language to English, since in all likelihood English characters and linear format Math are going to typed within the zone. Presently, typing an inline equation requires the tricky sequence of Alt-= followed by Alt-Shift to switch the input to English. The fact input reverts to Hebrew as soon as you leave the math zone provides a slight mitigation, but if that’s the behavior, it makes even more sense for the math zone insertion to switch the input language to one suitable for math.

    Another, more acute issue is that RTL text is poorly supported in math zones. For example, if one tries to insert two words in Hebrew under a = sign with below, the second word will appear to right of the first word, which is clearly wrong for RTL.

    Looks like it is too late for Office 2007 but I hope to see Word 2010 address RTL and math interaction better.

    I also think integrating math zone support and the linear format input facility into OneNote would be a killer feature. OneNote is essentially useless for math and science classes as long as it lacks support for editable equations. Indeed, OneNote doesn’t even support inserting OLE objects. An Office application, no less!

  2. Marie Achim says:

    I have a problem using a specific type of bracket, <>, when I write an equation. With the others kinds of brackets like (), [], {}, their height changes depending on the content we put in (small for a number, bigger for a fraction). But not the set <>. However, the same set plus a separator < | > changes height.

    Is it a known problem for Word 2007 or am I doing something wrong?

    I’m not sure if this blog is the correct place to ask this question. If not, could you tell me where I could find some help on that subject.


    PS. I’m using the french version of Word 2007! Could this be the cause of the problem?

  3. MurrayS says:

    The characters < and > are not considered to be brackets in Office math. They are the relational operators less than and greater than. For angle brackets, use bra and ket (U+27E8 and U+27E9). These brackets expand as you desire. The names bra and ket come from Dirac notation used in quantum mechanics. You can also use TeX’s langle and rangle, respectively.

  4. Marie Achim says:

    Sorry, may be I wasn’t clear. English is not my first language.

    I’m taking about writing an equation in Word 2007 (part of Office 2007) with the tool "Equation", represented by the greek letter pi, found in the menu "Insertion". The <> is in fact a set of brackets in Word 2003 AND in Word 2007, just like () and {}.

    It worked perfectly in Word 2003 but not in Word 2007.

    You get access to the set <> at the same place you find the others sets of brackets.

    You are talking about Office Math. I guess it is different than Word 2007.

    With this new info, can you help?

    Thanks in advance.

  5. MurrayS says:

    Office math includes Word 2007 and RichEdit 6.0. Word 2007 uses bra and ket for the angle brackets you want. Or, equivalently, langle and rangle. The ASCII characters < and > are reserved for the less-than and greater-than operators. Office math is based on Unicode and Unicode does not consider the ASCII < and > to be brackets.