Examples of Vectors and Matrices in Stateflow Charts :: Using Vectors and Matrices in Stateflow Charts (Stateflow®)

The state get_payload stores complex data in the vector frame, which is of size 221. The entry action assigns the value of (IQ * phasor) to the first element of frame. The during action assigns the next 220 values of (IQ * phasor) to successive elements of frame until you store 221 elements. (For more information, see Using the temporalCount Operator to Index a Vector.)

Scalar Expansion of a Vector

In the second outgoing transition of the state look_for_sync, the transition action frame = 0 resets all elements of the vector frame to 0 via scalar expansion. (For more information, see Using Scalar Expansion to Assign Values of a Vector or Matrix.)

Physics Example

The demo model sf_pool is an example of using matrices in a Stateflow chart to simulate the opening shot on a pool table.

How the Model Works

The model consists of the following blocks.

Model Component	Description
Init chart	Initializes the position and velocity of the cue ball.
Pool chart	Calculates the two-dimensional dynamics of each ball on the pool table.
Plot block	Animates the motion of each ball during the opening shot.
Vel scope	Displays the velocity of each ball during the opening shot.
Clock	Provides the instantaneous simulation time to the Plot block.

Storage of Two-Dimensional Data in Matrices

To simulate the opening shot, the Pool chart stores two-dimensional data in matrices.

To store values for...	The Pool chart uses...
The instantaneous position of each ball	The 15-by-2 matrix `p`
The instantaneous velocity of each ball	The 15-by-2 matrix `v`
Friction and interaction forces acting on each ball	The 15-by-2 matrix `v_dot`
Boolean data on whether any two balls are in contact	The 15-by-15 matrix `ball_interaction`

Calculation of Two-Dimensional Dynamics of Each Ball

The Pool chart calculates the motion of each ball on the pool table using MATLAB functions that perform matrix calculations.

MATLAB Function	Description
`frictionForce`	Calculates the friction force acting on each ball.
`getBallInteraction`	Returns a matrix of Boolean data on whether any two balls are in contact.
`hasBallInteractionChanged`	Returns 1 if ball interactions have changed and 0 otherwise.
`initBalls`	Initializes the position and velocity of every ball on the pool table.
`interactionForce`	Calculates the interaction force acting on each ball.
`isAnyBallGoingToStop`	Returns 1 if any ball has stopped moving and 0 otherwise.
`isAnyBallNewlyPocketed`	Returns 1 if any ball has been newly pocketed and 0 otherwise.
`isAnyBallOutOfBounds`	Returns true if any ball is out of bounds and false otherwise.
`nearHole`	Returns true if a ball is near a pocket on the pool table and false otherwise.
`pocketNewBalls`	Sets the velocity of a ball to 0 if it has been pocketed.
`resetBallsPosAndVel`	Resets the position and velocity of any ball that is out of bounds.
`updateStopFlags`	Keeps track of which balls have stopped moving.

Running the Demo Model

To run the demo model, follow these steps:

Type sf_pool at the MATLAB command prompt.
Start simulation.
Click anywhere in the animated pool table to specify the initial position of the cue ball.
Click a different spot to specify the initial velocity of the cue ball.
Watch the balls move across the pool table.

Best Practices for Vectors and Matrices in Stateflow Charts

Using Variable-Size Data in Stateflow Charts

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