The less than (<) block produces an output signal of 1 if and only if input signal x1 is less than 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 t < 4 then y = 1; else y = 0
Assume that t is simulation time. This system can be realized as:
By multiplying a constant value one with the output of the < block, y is guaranteed to assume a value of zero until the inequality is true. When the inequality is true, y assumes a value equal to the output of the * block.
2. Modified if-then-else construct
The previous example can also be realized as:
The key difference in implementation is the use of a merge block rather than a * block. The merge block explicitly depicts the if-then-else structure; the * block is a shortcut and can lead to confusion.