What's the difference between a control, constant, dependent and an independent variable?

A single loop control system consists of an input and several outputs.





The ';input'; is an independent variable.





The ';outputs'; are all dependent, or controlled, variables.





There are no ';constant'; variables. Some constants are set for calibration purposes, in which case they are called ';parameters';, or ';parametric variables.';


,What's the difference between a control, constant, dependent and an independent variable?
In computer science and mathematics, a variable (sometimes called an object or identifier in computer science) is a symbolic representation used to denote a quantity or expression. In mathematics, a variable often represents an ';unknown'; quantity that has the potential to change; in computer science, it represents a place where a quantity can be stored. Variables are often contrasted with constants, which are known and unchanging.





Dependent and independent variables refer to values that change in relationship to each other. The dependent variables are those that are observed to change in response to the independent variables.





Controlled variables are also important to identify in experiments. They are the variables that are kept constant to prevent their influence on the effect of the independent variable on the dependent.


In summary:





The independent variable answers the question ';What do I change?';.


The dependent variables answer the question ';What do I observe?';.


The controlled variables answer the question ';What do I keep the same?';.

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