The sign2Heaviside command rewrites signum function (see Section 8.3.2) to Heaviside step function (see Section 8.3.2) in an expression by using the identity sign(x)=2θ(x)−1.
The Heaviside2sign command has the same syntax but does the opposite of sign2Heaviside, i.e. it replaces all instances of Heaviside function by signum according to the identity θ(x)=sign(x)+1/2.