The Mathematical Symbol "Star Operator (⋆)"

The "Star Operator" (⋆)

The ⋆ symbol, also known as the "Star Operator", is used in different contexts across various mathematical and computational domains. Its interpretation can vary depending on the area of application.

Contextual Uses of the Star Operator

While the ⋆ symbol might look like a regular asterisk or star to many, its application can be quite diverse:

  • Algebra: Sometimes used as a notation for convolution in the realm of function analysis.
  • Computer Science: In some programming languages, the ⋆ might represent a pointer or be used as a wildcard character in search patterns.
  • Databases: In SQL, the ⋆ is used to select all columns from a table.
  • Mathematics: In general, it can denote a special operation or function that has been defined for a specific use case.

Examples

Here are some examples of how the ⋆ might be used:

  1. In the Fourier analysis realm, if \( f \) and \( g \) are two functions, their convolution could be represented as \( f ⋆ g \).
  2. In programming, a statement like `int ⋆ p;` in C or C++ declares a pointer to an integer.
  3. In SQL, a query like `SELECT ⋆ FROM table_name;` will retrieve all columns from the specified table.

Notation

The placement and usage of the ⋆ operator depend entirely on its context. For instance, in the realm of convolution, it's placed between two functions. In programming, its placement determines whether it's pointing to a value's memory location or if it's dereferencing a pointer.

Conclusion

The ⋆ symbol is versatile and carries different meanings in various contexts. Understanding its meaning requires knowledge of the specific domain where it's being applied. While it looks simple, its applications are broad, ranging from mathematics to computer programming.

Mathematical symbol 'Star Operator'

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Codes for the ⋆ Symbol

The Symbol⋆
Alt CodeAlt 8902
HTML Code⋆
HTML Entity⋆
CSS Code\22C6
Hex Code⋆
UnicodeU+22C6

How To Insert the ⋆ Symbol

(Method 1) Copy and paste the symbol.

The easiest way to get the ⋆ symbol is to copy and paste it into your document.

Bear in mind that this is a UTF-8 encoded character. It must be encoded as UTF-8 at all stages (copying, replacing, editing, pasting), otherwise it will render as random characters or the dreaded �.

(Method 2) Use the "Alt Code."

If you have a keyboard with a numeric pad, you can use this method. Simply hold down the Alt key and type 8902. When you lift the Alt key, the symbol appears. ("Num Lock" must be on.)

(Method 3) Use the HTML Decimal Code (for webpages).

HTML TextOutput
<b>My symbol: &#8902;</b>My symbol: ⋆

(Method 4) Use the HTML Entity Code (for webpages).

HTML TextOutput
<b>My symbol: &Star;</b>My symbol: ⋆

(Method 5) Use the CSS Code (for webpages).

CSS and HTML TextOutput
<style>
span:after {
content: "\22C6";}
</style>
<span>My symbol:</span> 		My symbol: ⋆

(Method 6) Use the HTML Hex Code (for webpages and HTML canvas).

HTML TextOutput
<b>My symbol: &#x22C6;</b>My symbol: ⋆
On the assumption that you already have your canvas and the context set up, use the Hex code in the format 0x22C6 to place the ⋆ symbol on your canvas. For example:
JavaScript Text
const x = "0x"+"E9"
ctx.fillText(String.fromCodePoint(x), 5, 5);
Output

⋆

(Method 7) Use the Unicode (for various, e.g. Microsoft Office, JavaScript, Perl).

The Unicode for ⋆ is U+22C6. The important part is the hexadecimal number after the U+, which is used in various formats. For example, in Microsoft Office applications (e.g. Word, PowerPoint), do the following:
TypeOutput
22C6
[Hold down Alt]
[Press x]		⋆
(The 22C6 turns into ⋆. Note that you can omit any leading zeros.)
In JavaScript, the syntax is \uXXXX. So, our example would be \u22C6. (Note that the format is 4 hexadecimal characters.)
JavaScript TextOutput
let str = "\u22C6"
document.write("My symbol: " + str)		My symbol: ⋆