Contents of Understanding User Selections

Understanding User Selections

You can restrict the computation to a selection you have made and so override Scientific Notebook's automatic choice. (Recall that you can select a piece of mathematics by holding down the left mouse button while moving the mouse; your selection is the information that appears on the screen in reversed colors.)

There are two options for applying operations to your selection—one displays the result of the operation but leaves the selection intact, and the other replaces the selection with the result of the operation. Following are two examples illustrating the behavior of the system for each of these two options.

$\blacktriangleright$ To operate on a selection

Use the mouse or press SHIFT+ARROW to select 2 + 3 in the expression 2 + 3 - x. From the Maple menu, choose Evaluate. Scientific Notebook puts the answer to the right of the expression, following a colon (:).

2 + 3 - x : 5

Use the mouse or press SHIFT+ARROW to select (x + y)³ within the expression $\left(\vphantom{ x+y}\right.$ x + y $\left.\vphantom{ x+y}\right)^{{3}}_{}$ (7x - 13y)³ + sin²x. From the Maple menu, choose Expand. Scientific Notebook puts the answer to the right of the whole expression, following a colon (:).

$\left(\vphantom{ x+y}\right.$ x + y $\left.\vphantom{ x+y}\right)^{{3}}_{}$ (7x - 13y)³ + sin²x : x³ +3x²y + 3xy² + y³

In general, Scientific Notebook assumes that the result of applying an operation to a user selection is not equal to the entire original expression, so it places the result at the end of the mathematics, separated by something in text (in this case, a colon). You can then use the word-processing capabilities of Scientific Notebook to put the result where you want it in your document.

You can replace part of an expression with the result of a computation on that part.

$\blacktriangleright$ To replace a selection

To replace 394876 + 205583 by its value, select the entire expression, hold down CTRL , and click itbpF0.3009in0.3009in0.0701inevaluate.wmf or choose Evaluate. Your selection 394876 + 205583 is replaced by its value

600459

To replace $\left(\vphantom{ x-2y}\right.$ x - 2y $\left.\vphantom{ x-2y}\right)^{{2}}_{}$ in the expression $\left(\vphantom{ x-2y}\right.$ x - 2y $\left.\vphantom{ x-2y}\right)^{{2}}_{}$ $\left(\vphantom{ 7x-13y}\right.$ 7x - 13y $\left.\vphantom{ 7x-13y}\right)$ $\left(\vphantom{ x^{2}+1}\right.$ x² + 1 $\left.\vphantom{ x^{2}+1}\right)$ with its expansion, select $\left(\vphantom{ x-2y}\right.$ x - 2y $\left.\vphantom{ x-2y}\right)^{{2}}_{}$ , hold down the CTRL key, and click itbpF0.3009in0.3009in0.0701incxpand.wmf or choose Expand. Your selection, $\left(\vphantom{ x-2y}\right.$ x - 2y $\left.\vphantom{ x-2y}\right)^{{2}}_{}$ , is replaced by its expansion. The expansion has no parentheses around it, but since it remains selected, you can click itbpF0.3009in0.3009in0.0701inparens.wmf to add the needed parentheses.

(x² -4xy + 4y²)(7x - 13y)(x² + 1)

You can return the expression to a factored form by selecting $\left(\vphantom{ x^{2}-4xy+4y^{2}}\right.$ x² -4xy + 4y² $\left.\vphantom{ x^{2}-4xy+4y^{2}}\right)$ , holding down the CTRL key, and choosing Factor.

To factor in place the subexpression - b + b² inside the expression a - b + b², first insert a + before the - b to get a + - b + b², then select the expression - b + b², and while holding down the CTRL key, apply Factor.

a + b $\left(\vphantom{ -1+b}\right.$ -1 + b $\left.\vphantom{ -1+b}\right)$

Important This ``computing in place''— that is, holding down the CTRL key as you choose an operation from the Maple menu—is a key feature of Scientific Notebook. It provides a convenient way for you to manipulate expressions into the forms you desire.