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Physlib.QuantumMechanics.OneDimension.HilbertSpace.SchwartzSubmodule

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definition

Continuous linear inclusion S(R,C)L2(R,C)\mathcal{S}(\mathbb{R}, \mathbb{C}) \to L^2(\mathbb{R}, \mathbb{C})

#schwartzIncl

The continuous complex-linear map ι:S(R,C)L2(R,C)\iota : \mathcal{S}(\mathbb{R}, \mathbb{C}) \to L^2(\mathbb{R}, \mathbb{C}) that embeds the space of Schwartz functions S(R,C)\mathcal{S}(\mathbb{R}, \mathbb{C}) into the Hilbert space of square-integrable functions L2(R,C)L^2(\mathbb{R}, \mathbb{C}) with respect to the Lebesgue measure.

theorem

The inclusion ι:S(R,C)L2(R,C)\iota : \mathcal{S}(\mathbb{R}, \mathbb{C}) \to L^2(\mathbb{R}, \mathbb{C}) is injective

#schwartzIncl_injective

The continuous linear map ι:S(R,C)L2(R,C)\iota : \mathcal{S}(\mathbb{R}, \mathbb{C}) \to L^2(\mathbb{R}, \mathbb{C}) that embeds the space of Schwartz functions S(R,C)\mathcal{S}(\mathbb{R}, \mathbb{C}) into the Hilbert space of square-integrable functions L2(R,C)L^2(\mathbb{R}, \mathbb{C}) is injective.

theorem

ι(ψ)=ψ\iota(\psi) = \psi almost everywhere for ψS(R,C)\psi \in \mathcal{S}(\mathbb{R}, \mathbb{C})

#schwartzIncl_coe_ae

Let S(R,C)\mathcal{S}(\mathbb{R}, \mathbb{C}) be the space of Schwartz functions and ι:S(R,C)L2(R,C)\iota : \mathcal{S}(\mathbb{R}, \mathbb{C}) \to L^2(\mathbb{R}, \mathbb{C}) be the continuous linear inclusion into the Hilbert space of square-integrable functions. For any Schwartz function ψS(R,C)\psi \in \mathcal{S}(\mathbb{R}, \mathbb{C}), its image ι(ψ)\iota(\psi) is equal to ψ\psi almost everywhere with respect to the Lebesgue measure.

theorem

The inner product of ι(ψ1)\iota(\psi_1) and ι(ψ2)\iota(\psi_2) is ψ1ψ2\int \overline{\psi_1} \psi_2

#schwartzIncl_inner

Let S(R,C)\mathcal{S}(\mathbb{R}, \mathbb{C}) be the space of Schwartz functions and let ι:S(R,C)L2(R,C)\iota : \mathcal{S}(\mathbb{R}, \mathbb{C}) \to L^2(\mathbb{R}, \mathbb{C}) be the continuous linear inclusion into the Hilbert space of square-integrable functions. For any two Schwartz functions ψ1,ψ2S(R,C)\psi_1, \psi_2 \in \mathcal{S}(\mathbb{R}, \mathbb{C}), the inner product of their images in the Hilbert space is given by the integral over the real line of the complex conjugate of ψ1\psi_1 multiplied by ψ2\psi_2: ι(ψ1),ι(ψ2)C=ψ1(x)ψ2(x)dx\langle \iota(\psi_1), \iota(\psi_2) \rangle_{\mathbb{C}} = \int_{-\infty}^{\infty} \overline{\psi_1(x)} \psi_2(x) \, dx