In a system of
differential equations used to describe a time-dependent process, a forcing function is a function that appears in the equations and is only a function of time, and not of any of the other variables.
In effect, it is a constant for each value of ''t''.
In the more general case, any nonhomogeneous source function in any variable can be described as a forcing function, and the resulting solution can often be determined using a superposition of linear combinations of the homogeneous solutions and the forcing term.
For example,
is the forcing function in the nonhomogeneous, second-order, ordinary differential equation:
References
Differential equations
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