# Lesson 9.1: Function Names

## Review

A letter or unbroken sequence of letters is standing alone when it is surrounded by spaces, hyphens, dashes, common punctuation, or indicator symbols. [*Rules of Unified English Braille* §2.6] A braille symbol that is standing alone can have a contraction (grade 2) meaning. When the grade 1 meaning is desired, grade 1 mode must be turned on. Grade 1 mode is turned on by grade 1 indicators or the numeric indicator. The letters a, i, and o do not require grade 1 indicators.

## Explanation

Function names are used in both mathematical and science expressions. Function names are often abbreviated in print. Follow print for spelling and capitalization of the function name. Function names may be preceded or followed by a lower or upper-case letter. When the letter is written in italics to indicate it is a variable, omit the italics in braille.

Common function names include sine (sin), cosine (cos), tangent (tan), secant (sec), logarithm (log), to name a few.

When a function name is directly preceded or followed by a number, the number should be written unspaced from the function name.

### Example 1

$4\mathrm{tan}45\xb0$

⠼⠙⠞⠁⠝⠼⠙⠑⠘⠚

A function name may be preceded or followed by an unspaced letter in print. A space may be needed to remove ambiguity as to where the function name begins and ends. No space is needed if the function name is already separated from the letter by a bracket or braille indicator. If a function name is directly followed by a lower case Latin letter with no intervening brackets or braces, a space should be inserted between the function name and the letter. A grade 1 indicator may be required with the letter.

### Example 2

$\mathrm{cos}x$

⠉⠕⠎⠀⠰⠭

### Example 3

$\mathrm{tan}\left(x\right)$

⠞⠁⠝⠐⠣⠭⠐⠜

### Example 4

$\mathrm{cos}\theta $

⠉⠕⠎⠨⠹

When a function name is preceded directly by a lower or upper case Latin letter with no intervening braille indicators or brackets, a space must be inserted between the letter and the function name. A grade 1 indicator may be required with the letter.

### Example 5

$x\mathrm{sin}30$

⠰⠭⠀⠎⠔⠼⠉⠚

When the function name sine or sin follows a numeral, the groupsign "in" not used because grade 1 mode is in effect.

### Example 6

$5\mathrm{sin}3x$

⠼⠑⠎⠊⠝⠼⠉⠭

### Example 7

$1=\mathrm{sin}45\xb0$

⠼⠁⠀⠐⠶⠀⠎⠔⠼⠙⠑⠘⠚

Complex equations are best enclosed in grade 1 passage indicators to ensure that letters standing alone and indicators such as superscript, subscript, fractions, radicals, arrows and shapes are well defined without the need for grade 1 symbol indicators.

### Example 8

$\mathrm{cos}30\xb0=\frac{\sqrt{3}}{2}$

⠰⠰⠰⠉⠕⠎⠼⠉⠚⠘⠚⠀⠐⠶⠀⠷⠩⠼⠉⠬⠨⠌⠼⠃⠾⠰⠄

### Example 9

${\mathrm{sin}}^{2}45\xb0={\mathrm{cos}}^{2}45\xb0$

⠰⠰⠰⠎⠊⠝⠔⠼⠃⠼⠙⠑⠘⠚⠀⠐⠶⠀⠉⠕⠎⠔⠼⠃⠼⠙⠑⠘⠚⠰⠄

### Example 10

$y=x\mathrm{log}x$

⠰⠰⠰⠽⠀⠐⠶⠀⠭⠀⠇⠕⠛⠀⠭⠰⠄