- #1

maxbashi

- 18

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**Why is the right side called the "input?"**

I'm looking at linear, 1st order ODEs, like

y' + p(t)x = q(t)

The notes I'm looking at are calling q(t) the "input" of the system, but I'm not sure why. I understand how to solve the equations, but I must be looking at it differently or something. To quote the notes:

The left hand side represents the SYSTEM.

The right hand side represents an outside influence on the system: it's a "signal," the "input signal." A "signal" is just a function of time.

The system responds to the input signal and yields the function x(t), "output signal."

I guess I'm just not intuitively understanding the way the author is looking at ODEs. Any help?