**Symbol Dynamics ^{®} EXP^{®}**

The Scientific Word Processor

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This document highlights differences between using EXP and using Microsoft Word 2000 to create documents containing mathematics.

In order to compare EXP with Word, one needs to understand the approach each program takes to the problem of providing mathematics word processing in the Windows environment.

Word's approach to allowing mathematics to be incorporated into a document is to provide an add-on (ActiveX/OLE) equation editor that allows the user to create and edit math expressions. The equation editor provides all the math editing and formatting functionality because Word itself knows nothing about mathematics typography. To incorporate a formula into a Word document, you instruct Word that you want to insert an Equation object into the document. Word then starts the equation editor so you can compose the equation. To incorporate the formula into the Word document, the equation editor inserts the formula as a graphic.

There are many flaws with this approach, but perhaps the most striking one is that it regards mathematics as being like a special kind of graphic. Most documents that use mathematics do not have one or two uses of mathematical notation per page (as one might with graphics) but rather they have dozens and dozens.

EXP's approach to allowing mathematics to be incorporated into a document is to provide a specialized word processor that fully integrates text and mathematics word-processing capabilities.

The amount of work and expertise involved in implementing this integrated approach is much greater than for Word's add-on approach. For this reason, EXP for Windows is the only WYSIWYG program that takes this approach. The reason for taking the time to develop a specialized word processor for mathematics was that the add-on approach is very limited and no amount of work can solve its underlying problems.

The following subsections describe some of the major differences between using EXP and using Word to create documents containing mathematics.

- To type math with Word, you must constantly switch back and forth between "Word mode" and "Equation Editor mode". This switch is not only annoying but can be very time consuming as well. With EXP, all math and text editing is performed within an integrated environment.
- Using EXP to type math is much faster and more convenient than using Word. For example, consider the steps necessary to type the LaTeX symbol called "mapsto". In Word you
would perform the following steps:
- Press ALT, I, O to display the Object dialog box.
- Press DOWN multiple times to select the entry titled "Microsoft Equation 3.0".
- Press ENTER. When the equation editor starts, Word's document window suddenly shifts up as Word's toolbars are hidden and the equation editor's toolbar appears.
- Click the mouse to open the drop-down symbol palette for the mapsto symbol. You have to remember which symbol palette contains a given symbol or otherwise you must spend time hunting around for it.
- Click the mouse on the symbol palette to choose the mapsto symbol.
- Press ESC to exit the equation editor and return to Word. At this point Word's document window will suddenly shift down as the equation editor's toolbar is hidden and Word's toolbars appear.

- In EXP you only have to perform the following steps to insert the mapsto symbol:
- Press F4 to display the Symbol Box.
- Type mapsto.
- Press ENTER.

- Although Word itself provides many levels of undo, the equation editor has its own undo system that provides only a single level of undo. EXP can undo any text or math modification up to 128 levels.

- Word's equation editor introduces a huge storage overhead because it must store (for each formula) the native representation that can be edited by the equation editor and a
graphical representation that can be displayed by Word. In EXP, only the native EXP representation needs to be stored, and thus much less space is required to store documents.

As an example of the tremendous difference in storage requirements between Word and EXP, consider the following example. A Word document containing nothing except 256 occurrences of x-squared (x^2) is 167,424 bytes long. An EXP document containing the same thing is 3,948 bytes long. That means the Word document is 42 times larger than the EXP document.

- Word's equation editor does not allow an inline formula to be split at the end of a line. This is because a formula is just a graphic and a graphic cannot be split across two lines. You would have to split the formula manually into two subformulas separated by a space so that the formula could be split at the end of the line. If later editing or formatting changes caused the formula to appear on one line, you would have to delete the space and add the two subformulas back together again. EXP allows you to specify positions in a formula where EXP may split the formula if it needs to.
- Word's equation editor does not allow you to make use of text-processing features inside formulas. The line breaking situation described above is an example of how a text-processing feature can be useful inside a formula.
- It is not possible to use Word's find and replace commands on math expressions. Thus, the only way to perform a global replace on a math expression is to scroll through the document looking for occurrences of the expression and manually change them. In EXP, you can use the find and replace commands to find a math expression and replace it with another math expression.
- In Word, if you change the point size of your text, the point size of any formulas in that text will not change. Each formula's graphic would have to be individually selected and carefully sized so it appeared to be the same size as the surrounding text, an immensely tedious process. In EXP, the size of a formula is derived from the point size of the surrounding text. If you change the point size of a paragraph, all the math in the paragraph will immediately be reformatted.
- In Word, it is not possible for plain text in a formula to adapt to changes you make to the typeface of your text. This limitation is related to the sizing limitation described above. Because the text inside a formula is trapped inside a graphic, you cannot change it unless you manually edit the graphic with the equation editor. In EXP, there is no distinction between plain text that is or is not part of a formula.

- Because Word's equation editor only uses standard Windows fonts to display most mathematical symbols, math produced with Word does not look at all like math produced with LaTeX. By contrast, EXP provides custom TrueType symbol fonts that are derived from the fonts used by LaTeX. Math produced with EXP looks almost identical to math produced with LaTeX. Also, EXP implements much of the math formatting logic of LaTeX.
- Word's equation editor does not support the important distinction between inline mathematics and displayed equations. EXP automatically formats all math in a displayed equation according to the rules governing displayed equations as defined by the TeX typesetting system. EXP also automatically formats all math not entered into a displayed equation according to the rules governing inline math as defined by TeX. If you move or copy a math expression into or out of a displayed equation, EXP automatically reformats the expression in its new location.
- Word's formatting and rendering software for text is separate and isolated from the equation editor's formatting and rendering software for math. Communication between the two does not occur. This implies that it is not possible for the equation editor to optimize its formatting based on conditions in the document. For example, in Word, a given formula is only formatted once, when it is originally created. If you later change the size of the formula's graphic in the document, the formula is not reformatted and the quality of the result will be suboptimal. In EXP, the process of formatting and displaying math and text is unified. Every time you make a change that should affect the formatting of a formula, the formula is automatically reformatted. Also, because EXP has a unified formatting and rendering engine that handles both text and mathematics, EXP provides many performance-enhancing optimizations that would be impossible for Word to provide.

- Word cannot convert documents to LaTeX. EXP can convert documents to LaTeX.
- Word's equation editor provides only about 150 symbols. EXP provides over 700 symbols.
- Upgrades to Word's equation editor will not provide any benefits to existing documents. This is because the formatting of a formula is frozen in a graphic that is not reformatted when you open the document in Word. Thus, even if a new version of the equation editor were to provide improved formatting, it would not improve existing documents. With EXP, when improvements are made they automatically and immediately affect all documents, old and new.