Fungrim entry: a46f94

\int_{0}^{\infty} {e}^{-a t} \theta_{4}\!\left(x , i b t\right) \, dt = \sqrt{\frac{\pi}{a b}} \frac{\cosh\!\left(2 x \sqrt{\frac{\pi a}{b}}\right)}{\sinh\!\left(\sqrt{\frac{\pi a}{b}}\right)}

Assumptions:

a \in \mathbb{C} \;\mathbin{\operatorname{and}}\; \operatorname{Re}(a) > 0 \;\mathbin{\operatorname{and}}\; b \in \mathbb{C} \;\mathbin{\operatorname{and}}\; \operatorname{Re}(b) > 0 \;\mathbin{\operatorname{and}}\; x \in \left[-\frac{1}{2}, \frac{1}{2}\right]

References:

https://doi.org/10.1016/0022-0728(88)87001-3

TeX:

\int_{0}^{\infty} {e}^{-a t} \theta_{4}\!\left(x , i b t\right) \, dt = \sqrt{\frac{\pi}{a b}} \frac{\cosh\!\left(2 x \sqrt{\frac{\pi a}{b}}\right)}{\sinh\!\left(\sqrt{\frac{\pi a}{b}}\right)}

a \in \mathbb{C} \;\mathbin{\operatorname{and}}\; \operatorname{Re}(a) > 0 \;\mathbin{\operatorname{and}}\; b \in \mathbb{C} \;\mathbin{\operatorname{and}}\; \operatorname{Re}(b) > 0 \;\mathbin{\operatorname{and}}\; x \in \left[-\frac{1}{2}, \frac{1}{2}\right]

Definitions:

Fungrim symbol	Notation	Short description
`Integral`	$\int_{a}^{b} f(x) \, dx$	Integral
`Exp`	${e}^{z}$	Exponential function
`JacobiTheta`	$\theta_{j}\!\left(z , \tau\right)$	Jacobi theta function
`ConstI`	$i$	Imaginary unit
`Infinity`	$\infty$	Positive infinity
`Sqrt`	$\sqrt{z}$	Principal square root
`Pi`	$\pi$	The constant pi (3.14...)
`CC`	$\mathbb{C}$	Complex numbers
`Re`	$\operatorname{Re}(z)$	Real part
`ClosedInterval`	$\left[a, b\right]$	Closed interval

Source code for this entry:

Entry(ID("a46f94"),
    Formula(Equal(Integral(Mul(Exp(Mul(Neg(a), t)), JacobiTheta(4, x, Mul(Mul(ConstI, b), t))), For(t, 0, Infinity)), Mul(Sqrt(Div(Pi, Mul(a, b))), Div(Cosh(Mul(Mul(2, x), Sqrt(Div(Mul(Pi, a), b)))), Sinh(Sqrt(Div(Mul(Pi, a), b))))))),
    Variables(a, b, x),
    Assumptions(And(Element(a, CC), Greater(Re(a), 0), Element(b, CC), Greater(Re(b), 0), Element(x, ClosedInterval(Neg(Div(1, 2)), Div(1, 2))))),
    References("https://doi.org/10.1016/0022-0728(88)87001-3"))

Fungrim entry: a46f94

Topics using this entry