less than

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 connectors, “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 1 with the output of the < block, y is guaranteed to assume a value of 0 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.