atan2

Compute four-quadrant arctangent

• Library:

• Motor Control Blockset / Controls / Math Transforms

• 

Description

The atan2 block performs the four-quadrant arctangent on two real numbers.

Equations

This equation describes how the block computes the four-quadrant arctangent (θ).

$$Theta=a\tan 2(A,B)=\{\begin{array}{l}\arctan \left(\frac{A}{B}\right)\text{ if B>0,}\\ \arctan \left(\frac{A}{B}\right)+\pi \text{ if B<0 and A}\ge \text{0,}\\ \arctan \left(\frac{A}{B}\right)-\pi \text{ if B<0 and A<0,}\\ +\frac{\pi }{2}\text{ if B=0 and A>0, }\\ -\frac{\pi }{2}\text{ if B=0 and A<0,}\\ undefined\text{ if B=0 and A=0}\text{.}\end{array}$$

where:

$$-\pi <Theta\le \pi \text{ (Radians)}$$

Ports

Input

A — y-coordinate value (real number)

scalar

Real number on the y-axis that you provide as input to the block.

Data Types: single | double | fixed point

B — x-coordinate value (real number)

scalar

Real number on the x-axis that you provide as input to the block.

Data Types: single | double | fixed point

Output

θ — Angle represented by arctangent

scalar

Angle represented by arctangent. This is the angle made by a vector from the origin to a specified point (x,y) with the positive x-axis.

Data Types: single | double | fixed point

The following figure shows the representation of input values A, B, and arctangent on the x-y coordinate plane.

Parameters

Output unit — Unit of output values

Radians (default) | PerUnit

Unit of the output values.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

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

Version History

Introduced in R2020a