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integral_over_a_subset [2013/09/06 22:44] nikolaj |
integral_over_a_subset [2014/02/13 16:13] 127.0.0.1 external edit |
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===== Integral over a subset ===== | ===== Integral over a subset ===== | ||
- | ==== Definition ==== | + | ==== Set ==== |
| @#88DDEE: $\mathbb K = \overline{\mathbb R}\lor \mathbb C$ | | | @#88DDEE: $\mathbb K = \overline{\mathbb R}\lor \mathbb C$ | | ||
| @#88DDEE: $\langle X,\Sigma,\mu_X\rangle$ ... measure space | | | @#88DDEE: $\langle X,\Sigma,\mu_X\rangle$ ... measure space | | ||
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If $X=\mathbb R$, $a,b\in \mathbb R$, $a<b$ and the measure $\mu_X$ is such that single points have zero measure $\mu_X(\{a\})=\mu_X(\{b\})=0$ (like the standard [[Lebesgue measure]]), then we write | If $X=\mathbb R$, $a,b\in \mathbb R$, $a<b$ and the measure $\mu_X$ is such that single points have zero measure $\mu_X(\{a\})=\mu_X(\{b\})=0$ (like the standard [[Lebesgue measure]]), then we write | ||
- | ^ $\int_a^b\ f\cdot \mathrm d\mu_X\equiv\int_{[a,b]}\ f\cdot \mathrm d\mu_X$ ^ | + | ^ $\int_a^b\ f\ \mathrm d\mu_X\equiv\int_{[a,b]}\ f\ \mathrm d\mu_X$ ^ |
The zero measure of $a,b$ guaranties that we replace integrals over $[a,b)$, $(a,b]$ and $(a,b)$ by this one. | The zero measure of $a,b$ guaranties that we replace integrals over $[a,b)$, $(a,b]$ and $(a,b)$ by this one. | ||
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If $c,d\in \mathbb R$ are numbers with $c<d$, then if we write integral symbol $\int_d^c$ (notice the switched positions of $c$ and $d$ w.r.t. their ordering) we mean the negative of the integral over $[c,d]$ | If $c,d\in \mathbb R$ are numbers with $c<d$, then if we write integral symbol $\int_d^c$ (notice the switched positions of $c$ and $d$ w.r.t. their ordering) we mean the negative of the integral over $[c,d]$ | ||
- | ^ $\int_d^c\ f\cdot \mathrm d\mu_X\equiv -\int_c^d\ f\cdot \mathrm d\mu_X$ ^ | + | ^ $\int_d^c\ f\ \mathrm d\mu_X\equiv -\int_c^d\ f\ \mathrm d\mu_X$ ^ |
==== Parents ==== | ==== Parents ==== | ||
- | === Requirements === | + | === Context === |
[[Pointwise function product]], [[Characteristic function]] | [[Pointwise function product]], [[Characteristic function]] | ||
=== Refinement of === | === Refinement of === | ||
[[Function integral]] | [[Function integral]] |