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Mathlib

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ENNReal.tsum_mul_left

{α : Type u_1} {a : ENNReal} {f : α → ENNReal} : ∑' (i : α), a * f i = a * ∑' (i : α), f i

Mathlib.Topology.Algebra.InfiniteSum.ENNReal

Documentation
Real.tsum_exp_neg_mul_int_sq

{a : ℝ} (ha : 0 < a) : ∑' (n : ℤ), Real.exp (-Real.pi * a * ↑n ^ 2) = 1 / a ^ (1 / 2) * ∑' (n : ℤ), Real.exp (-Real.pi / a * ↑n ^ 2)

Mathlib.Analysis.SpecialFunctions.Gaussian.PoissonSummation

Documentation
Complex.tsum_exp_neg_mul_int_sq

{a : ℂ} (ha : 0 < a.re) : ∑' (n : ℤ), Complex.exp (-↑Real.pi * a * ↑n ^ 2) = 1 / a ^ (1 / 2) * ∑' (n : ℤ), Complex.exp (-↑Real.pi / a * ↑n ^ 2)

Mathlib.Analysis.SpecialFunctions.Gaussian.PoissonSummation

Documentation
Complex.tsum_exp_neg_quadratic

{a : ℂ} (ha : 0 < a.re) (b : ℂ) : ∑' (n : ℤ), Complex.exp (-↑Real.pi * a * ↑n ^ 2 + 2 * ↑Real.pi * b * ↑n) = 1 / a ^ (1 / 2) * ∑' (n : ℤ), Complex.exp (-↑Real.pi / a * (↑n + Complex.I * b) ^ 2)

Mathlib.Analysis.SpecialFunctions.Gaussian.PoissonSummation

Jacobi's theta-function transformation formula for the sum of `exp -Q(x)`, where `Q` is a negative definite quadratic form.

Documentation
EisensteinSeries.qExpansion_identity

{k : ℕ} (hk : 1 ≤ k) (z : UpperHalfPlane) : ∑' (n : ℤ), 1 / (↑z + ↑n) ^ (k + 1) = (-2 * ↑Real.pi * Complex.I) ^ (k + 1) / ↑k.factorial * ∑' (n : ℕ), ↑n ^ k * Complex.exp (2 * ↑Real.pi * Complex.I * ↑z) ^ n

Mathlib.NumberTheory.ModularForms.EisensteinSeries.QExpansion

This is one key identity relating infinite series to q-expansions which shows that `∑' n, 1 / (z + n) ^ (k + 1) = ((-2 π I) ^ (k + 1) / k !) * ∑' n, n ^ k q ^n` where `q = cexp (2 π I z)`.

Documentation

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conclusion matches tsum _ = _ * tsum _