fixed.cordicReciprocal

Fixed-point reciprocal using CORDIC

Since R2021b

Syntax

y = fixed.cordicReciprocal(u,OutputType)

Description

y = fixed.cordicReciprocal(u,OutputType) returns 1./u with the output cast to the data type specified by OutputType.

Examples

Reciprocal Using CORDIC

u = fi(10);
outputType = fi([],1,32,24);
y = fixed.cordicReciprocal(u,outputType)

y = 

    0.1000

          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Signed
            WordLength: 32
        FractionLength: 24

Input Arguments

u — Value to take reciprocal of

scalar | vector | matrix | multidimensional array

Value to take reciprocal of, specified as a scalar, vector, matrix, or multidimensional array.

• If u is a floating-point type, then OutputType must specify a floating-point data type.

• If u is a built-in integer type, then OutputType must specify a built-in integer data type.

• If u is a fixed-point type, then OutputType must specify a fixed-point data type.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fi
Complex Number Support: Yes

OutputType — Data type of output

fi object | numerictype object | Simulink.NumericType object

Data type of the output, specified as a fi object, numerictype, or Simulink.NumericType object.

• If num is a floating-point type, den must also be a floating-point type and OutputType must specify a floating-point data type.

• If num is a built-in integer type, den must also be a built-in integer type and OutputType must specify a built-in integer data type.

• If num is a fixed-point type, den must also be a fixed-point type and OutputType must specify a fixed-point data type.

Example: fi([],1,16,15)

Example: numerictype(1,16,15)

Example: fixdt(1,16,15)

More About

CORDIC

CORDIC is an acronym for COordinate Rotation DIgital Computer. The Givens rotation-based CORDIC algorithm is one of the most hardware-efficient algorithms available because it requires only iterative shift-add operations (see References). The CORDIC algorithm eliminates the need for explicit multipliers. Using CORDIC, you can calculate various functions such as sine, cosine, arc sine, arc cosine, arc tangent, and vector magnitude. You can also use this algorithm for divide, square root, hyperbolic, and logarithmic functions.

Increasing the number of CORDIC iterations can produce more accurate results, but doing so increases the expense of the computation and adds latency.

Algorithms

For fixed-point input u, fixed.cordicReciprocal wraps on overflow for division by zero. The behavior for fixed-point division by zero is summarized in the table below.

Wrap Overflow	Saturate Overflow
0/0 = 0	0/0 = 0
1/0 = 0	1/0 = upper bound
-1/0 = 0	-1/0 = lower bound

For floating-point inputs, fixed.cordicReciprocal follows IEEE^® Standard 754.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Slope-bias representation is not supported for fixed-point data types.

Fixed-Point Conversion

Design and simulate fixed-point systems using Fixed-Point Designer™.

Slope-bias representation is not supported for fixed-point data types.

Version History

Introduced in R2021b