In applied sciences, by systems with distributed parameters we mean systems described by partial differential equations. The heat diffusion equation
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% aiaaikdaaaaaaaGccaGLOaGaayzkaaaaaa!4FD2!]]</EquationSource><EquationSource Format="TEX"><![CDATA[$$\frac{{\partial Q}}{{\partial t}} = a\left( {\frac{{{\partial ^2}Q}}{{\partial x_1^2}} + \ldots + \frac{{{\partial ^2}Q}}{{\partial x_n^2}}} \right)$$
(7.0.1)
or the wave equation
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% daaaaaaaGccaGLOaGaayzkaaaaaa!51B8!]]</EquationSource><EquationSource Format="TEX"><![CDATA[$$\frac{{{\partial ^2}Q}}{{\partial {t^2}}} = a\left( {\frac{{{\partial ^2}Q}}{{\partial x_1^2}} + \ldots + \frac{{{\partial ^2}Q}}{{\partial x_n^2}}} \right)$$
(7.0.2)
are examples of such systems.