Block Inputs: Two scalar inputs.
The greater than or equal to (>=) block produces an output signal of 1 if and only if input signal x1 is greater than or equal to input signal x2. Otherwise, the output is 0. On the connector tabs, “l” represents x1 and “r” represents x2.
If you right click the >= block, the Boolean block menu appears allowing you to assign a different function to the block.
1. Simple if-then-else construct
Consider a variable y such that:
If x ≥ 0.5 then y = sin(t); else y = 1
where t is simulation time. Let x be a unit step delayed by 3s. This is usually represented as u(t - 3). This system can be realized as shown below.
Until the onset of the step input at t = 3s, the Boolean inequality x ≥ 0.5 evaluates to false and y takes on a value of 1. At t = 3s, the Boolean inequality evaluates to true and remains true for the duration of the simulation duration. Consequently, from this point onwards, y takes on the value of sin(t).