2.1 The basics  (Page 3/5)

This parenthetical structure can also be visualized as a tree-like structure. See the MathML Editor: Manual for an example .

By moving our cursor left and right, we move deeper in or out of these parenthetical or tree-like structures, represented by a longer path name, and a smaller unit of shaded math. The Path and shading lets us know the context of our cursor, i.e. where within the parenthetical or tree-like structure our cursor is. Essentially, navigating to different contexts of the MathML expression lets us place new expressions anywhere we want, as we'll show below .

Editing expressions

Adding an argument to an existing operation

Be sure the editing area of the MathML editor contains the expression we entered , $x^2+bx$ . Let's change this to $x^2+bx+c$ .

To do this, we will have to add an argument to the addition operation. Move your cursor to the end of the expression by clicking on the last $x()$ and then pushing the right arrow key a couple of times to move the cursor to the right of the times operation. Then type in +c and press Enter .

You do not always have to add on to the right-hand side of an expression. Try moving your cursor to the beginning of the expression, typing in c+ followed by Enter . Experiment with adding more arguments to the plus operation just after the power operation or just before the times operation.

Creating a new operation

In our example, $x^2+bx+c$ , let's change $x^2$ to $ax^2$ . We are not adding an argument to an existing operation, because $x()$ and 2 are arguments of a power operator, while we want to make the entire power operation one argument of a times operation. The other argument will be the new element that we are adding, $a()$ .

The underlying structure of our new expression will look something like this: ( ( (a) ( (x)^(2) ) ) + ( (b)*(x) ) + (c) )

For this we will need to choose the context of our cursor carefully, or we will get different math. Make sure your cursor is on the left hand side of the power operation, the path says Path: / plus / power and that $x^2$ has a light grey background. This means the context of the cursor is the expression $x^2$ , which is good. We only want to multiply $x^2$ by $a()$ , nothing more and nothing less.

Then type in a* and press Enter . The MathML should display as:

$ax^2+bx+c$

What if our cursor had been in a different context when we typed in a* ? We could have moved our cursor farther to the left so that the context was the entire plus operation, where the path bar would read Path: / plus and the entire expression would have had a light grey background. In this case, typing in a* would have affected the entire grey area and would have resulted in this display:

$a(x^2+bx+c)$

If our cursor was next to the $x()$ within the $x^2$ term, a block would appear around the $x()$ and the path bar would read Path: / plus / power / ci . Typing in a* next to the $x()$ in the block would mean that now the quantity $ax$ would be squared and would result in this display:

$(ax)^2+bx+c$

Inserting expressions into a module

Let's put our expression $ax^2+bx+c$ into a module we're editing.

The MathML editor won't automatically insert your MathML expression into a module. You will have to copy and paste the MathML code. You can paste it into any module you wish, not only the module that you first accessed the MathML popup window from. The popup window can remain open even if you edit several different modules, but once you close it all contents of the editor will be lost.