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basic_tools:variational_calculus:functional [2018/03/14 15:58] iiqof |
basic_tools:variational_calculus:functional [2020/04/12 14:41] (current) jakobadmin |
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- | Let $\Omega(\mathcal{Q})$ be the set of functions $q:\mathbb{R} \to \mathcal{Q}$, then a //functional// S is a map | + | Let $\Omega(\mathcal{Q})$ be the set of functions $q:\mathbb{R^n} \to \mathcal{Q}$, then a //functional// S is a map |
- | $$ | + | |
- | S:\Omega \to \mathbb{R}; S[q] \mapsto \alpha \in\mathbb{R} | + | $$ S:\Omega \to \mathbb{R}; S[q] \mapsto \alpha \in\mathbb{R} .$$ |
- | $$ | + | |
So we can see how a functional is a //function of functions// as we said before, this is the reason why the notation $S[\cdot]$ instead of $S(\cdot)$, to remind that it is more that the eyes meet. | So we can see how a functional is a //function of functions// as we said before, this is the reason why the notation $S[\cdot]$ instead of $S(\cdot)$, to remind that it is more that the eyes meet. | ||
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- | But there can be other functionals: maximum/minimum value of a function, value at point $x$... | + | But there can be other functionals: maximum/minimum value of a function, evaluation of the function at a point (i.e. a function is also a functional)... |