# Fixed Point Basics¶

A `FixedPoint`

object consists of:

A distinct number of bits

A distinct binary point position within those bits

to the left of the binary point are integer bits

to the right of the binary point are fractional bits

Properties that govern interactions with other built-in and

`FixedPoint`

objects

## Q Format¶

The `fixedpoint`

module utilizes the
“Q-format notation”
to describe the word length and binary point position:

**Qm.n**represents a signed fixed point number with m integer bits and n fractional bits (that is, m + n total bits). The most significant bit has a negative weight.**UQm.n**represents an unsigned fixed point number with m integer bits and n fractional bits (that is, m + n total bits). The most significant bit has a positive weight.

Furthermore:

Negative

**m**or**n**is not allowed.Total word length (

**m**+**n**) must be positive.Signed numbers must have

**m**greater than 0, while unsigned numbers can have**m**equal to 0, as long as total word length is positive.**n**can be 0 as long as total word length is positive.

Any deviation from the above specifications constitutes an invalid Q format.

Warning

Some notations reverse *m* and *n*. Some notations use *A* and *U* to
represent signed and unsinged numbers, respectively. Some notations do not
include the sign bit in the integer bits.

It is important to understand the Q format utilized by `fixedpoint`

because there are various formats in use throughout the industry.