ModularForm.isCuspForm_iff_coeffZero_eq_zero

∀ {k : ℤ} (f : ModularForm (Matrix.SpecialLinearGroup.mapGL ℝ).range k),
  f.IsCuspForm ↔ (PowerSeries.coeff 0) (UpperHalfPlane.qExpansion 1 ⇑f) = 0

For 𝒮ℒ modular forms, IsCuspForm is equivalent to the q-expansion having vanishing constant term.

Defined in: Mathlib.NumberTheory.ModularForms.CuspFormSubmodule
Cited by: 2 results in Mathlib
Foundations: Depth 295 from the axioms · uses propext, Classical.choice, Quot.sound

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