The BOX Tag

Example

<BOX>x^2^ - 1 <OVER> x + 1</BOX> = x - 1

Output:

The BOX tag in conjunction with the LEFT and RIGHT tags also allows one to "grow" stretchy delimiters to match the height of the enclosed expression. The stetchy delimiters that WebEQ recognizes are |, {, }, [, ], (, and ).

Example

<BOX>(<LEFT>1 + <BOX>1 <OVER> n</BOX>
<RIGHT>)</BOX>^n^ → e 

Output:

The BOX tag accepts an optional SIZE parameter which forces stretchy delimiters to grow larger than the enclosed expression. When used in this way, the permitted values of the SIZE parameter are MEDIUM and HUGE.

Example

<BOX SIZE=MEDIUM>|<LEFT><BOX SIZE=HUGE>(<LEFT>
(x-1)(x+1)<RIGHT>)</BOX>^2^<RIGHT>|</BOX>

Output:

Note that the SIZE parameter in the outer box is relative to the BOX expression it encloses, not the innermost expression. Thus a nested sequence of parentheses in MEDIUM boxes continues to grow without bound. Similarly, a sequence of nested HUGE delimiters grows more rapidly, and without bound.

Without the delimiters, the BOX tag can be used as "invisible" parentheses to make expressions unambiguous:

Example

<BOX>2^n^<OVER>3</BOX>&neq; <BOX>2<OVER>3^n^ </BOX>
&neq; <BOX>2<OVER>3</BOX>^n^

Output:

When the BOX tag is used as invisible parentheses, the SIZE parameter can be used to change the size of the enclosed expression. In this context, the permitted values are LARGER and SMALLER. A typical use would be to reduce the size of a fractional expression which is part of a larger expression. Comparing the following example with the same expression with the larger fraction above illustrates why this is desirable.

Example

<BOX>(<LEFT>1 + <BOX><BOX SIZE=SMALLER>1</BOX> <OVER>
<BOX SIZE=SMALLER>n</BOX></BOX><RIGHT>)</BOX>^n^→e

Output:

It is not possible to shrink an expression more than two sizes from the base font, nor is it possible to render an expression in a font larger than the base font.

The final uses of the BOX tag are a bit less common. By using CHOOSE or ATOP instead of OVER, the BOX tag facilitates the construction of binomial coefficients, and other "stacked" notations.

Example

<BOX>pq<ATOP>A</BOX>(n) = <BOX>(<LEFT>p<CHOOSE>q<RIGHT>)</BOX>^n^

Output:

Note that all these constructions descend below the baseline, and are thus not appropriate for putting text above an arrow and so on. That is better accomplished with the ABOVE tag.

Comments to: rminer@geom.umn.edu
Created: Fri Sep 8 11:39:00 1995 --- Last modified: Thu Mar 28 11:41:14 1996