**Block Inputs:** Two scalar inputs.

The != block produces an output signal of 1 if and only if
the two scalar input signals are not equal. On the connectors, “l” represents
*x*_{1} and “r” represents *x*_{2}.

If you right-click the != block, the Boolean block menu appears allowing you to assign a different function to the block.

**1. Comparing constants**

Consider a variable *y* such that:

If* t* ≠ 0.5 then *y* = cos(*t*); else
*y* = 0

where *t *is simulation time. This system can be
realized as shown below.

Until the value of *t* reaches 0.5, the
Boolean inequality *t* ≠ 0.5 evaluates to true, and *y* takes on a value of
cos(*t*). At *t* = 0.5s, the Boolean inequality evaluates to false,
and at the very next time step, returns to true, and remains true for the
duration of the simulation. Consequently, at the moment *t* = 0.5s,
*y* takes on the value of 0, and at every other point, *y* is equal to
cos(*t*).