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Physlib.QuantumMechanics.OneDimension.HilbertSpace.Gaussians

10 declarations

theorem

Gaussian functions are integrable

#gaussian_integrable

For any real numbers bb and cc such that b>0b > 0, the complex-valued function xeb(xc)2x \mapsto e^{-b(x-c)^2} is integrable on R\mathbb{R} with respect to the Lebesgue measure.

theorem

Gaussian functions are almost everywhere strongly measurable

#gaussian_aestronglyMeasurable

For any real numbers bb and cc such that b>0b > 0, the complex-valued function xeb(xc)2x \mapsto e^{-b(x-c)^2} is almost everywhere strongly measurable with respect to the Lebesgue measure on R\mathbb{R}.

theorem

Gaussian Functions Belong to the Hilbert Space

#gaussian_memHS

For any real numbers bb and cc such that b>0b > 0, the complex-valued Gaussian function xeb(xc)2x \mapsto e^{-b(x-c)^2} is an element of the Hilbert space of square-integrable functions on R\mathbb{R} (often denoted as L2(R)L^2(\mathbb{R})).

theorem

Integrability of ecxbx2e^{cx - bx^2} for b>0b > 0

#exp_mul_gaussian_integrable

For any real numbers bb and cc such that b>0b > 0, the function f(x)=ecxebx2f(x) = e^{cx} e^{-bx^2} is integrable on R\mathbb{R} with respect to the Lebesgue measure.

theorem

Integrability of ecxebx2e^{|cx|} e^{-bx^2} for b>0b > 0

#exp_abs_mul_gaussian_integrable

For any real numbers bb and cc such that b>0b > 0, the function f(x)=ecxebx2f(x) = e^{|cx|} e^{-bx^2} is integrable on R\mathbb{R} with respect to the Lebesgue measure.

theorem

fH    f(x)eb(xc)2L1f \in \mathcal{H} \implies f(x) e^{-b(x-c)^2} \in L^1

#mul_gaussian_mem_Lp_one

Let f:RCf: \mathbb{R} \to \mathbb{C} be a function in the Hilbert space H\mathcal{H} (the space of square-integrable functions L2(R)L^2(\mathbb{R})). For any real numbers bb and cc such that b>0b > 0, the function xf(x)eb(xc)2x \mapsto f(x) e^{-b(x-c)^2} is integrable, i.e., it belongs to L1(R)L^1(\mathbb{R}) with respect to the Lebesgue measure.

theorem

fH    f(x)eb(xc)2L2f \in \mathcal{H} \implies f(x) e^{-b(x-c)^2} \in L^2

#mul_gaussian_mem_Lp_two

Let f:RCf: \mathbb{R} \to \mathbb{C} be a function in the Hilbert space H\mathcal{H} (the space of square-integrable functions L2(R)L^2(\mathbb{R})). For any real numbers bb and cc such that b>0b > 0, the function xf(x)eb(xc)2x \mapsto f(x) e^{-b(x-c)^2} is square-integrable, i.e., it belongs to L2(R)L^2(\mathbb{R}).

theorem

fH    f(x)eb(xc)2L1f \in \mathcal{H} \implies |f(x)| e^{-b(x-c)^2} \in L^1

#abs_mul_gaussian_integrable

Let f:RCf: \mathbb{R} \to \mathbb{C} be a function in the Hilbert space H\mathcal{H} (the space of square-integrable functions L2(R)L^2(\mathbb{R})). For any real numbers bb and cc such that b>0b > 0, the function xf(x)eb(xc)2x \mapsto |f(x)| e^{-b(x-c)^2} is integrable with respect to the Lebesgue measure.

theorem

fH    ecxf(x)ebx2L1f \in \mathcal{H} \implies e^{cx} |f(x)| e^{-bx^2} \in L^1

#exp_mul_abs_mul_gaussian_integrable

Let f:RCf: \mathbb{R} \to \mathbb{C} be a function in the Hilbert space H\mathcal{H} (the space of square-integrable functions L2(R)L^2(\mathbb{R})). For any real numbers bb and cc such that b>0b > 0, the function xecxf(x)ebx2x \mapsto e^{cx} |f(x)| e^{-bx^2} is integrable with respect to the Lebesgue measure.

theorem

fH    ecxf(x)ebx2L1f \in \mathcal{H} \implies e^{|cx|} |f(x)| e^{-bx^2} \in L^1

#exp_abs_mul_abs_mul_gaussian_integrable

Let f:RCf: \mathbb{R} \to \mathbb{C} be a function in the Hilbert space H\mathcal{H} (the space of square-integrable functions L2(R)L^2(\mathbb{R})). For any real numbers bb and cc such that b>0b > 0, the function xecxf(x)ebx2x \mapsto e^{|cx|} |f(x)| e^{-bx^2} is integrable with respect to the Lebesgue measure.