created: 02/15/98; revised: 07/31/99, 01/18/00, 06/01/00, 05/11/03, 01/13/06, 07/15/10, 05/05/2012, 06/10/2014

Java includes the
primitive types `float`

and `double`

,
which hold floating point numbers.
When converted to characters, floating point numbers include a decimal point
followed by a decimal fraction.
For example, `3.14159`

and `-0.718802`

.

All of the familiar mathematical functions such as
*sine*, *log*, and *square root*
are available to your program in the Java `Math`

class.
These functions usually use arguments of type `double`

,
and usually return values of type `double`

.

Note: the character that is used to separate the whole part of the number from the fractional part depends on what country you are in. In the U.S. (and other countries with a historical tie to England) a dot is used. In many other countries (most of Europe and South America) a comma is used. These notes use a dot.

- Converting strings to double
- Keyboard input of floating point numbers
- The Math class
- Square root
- Trig functions
- PI
- Not a Number (NaN)

Which uses more bits: a Java `float`

or a Java `double`

?