FLINT3.7.0-dev
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acb_modular_lambda

Synopsis#include <flint/acb_modular.h>
void acb_modular_lambda(acb_t r, const acb_t tau, slong prec)source

Sets r to the modular lambda function \lambda(\tau) = \theta_2^4(0,\tau) / \theta_3^4(0,\tau), which is invariant under the subgroup \Gamma(2) of transformations (a, b; c, d) with a, d odd and b, c even.

Cite this page

The FLINT team, “acb_modular_lambda (acb_modular.h),” FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev, 2026. https://flintlib.org/doc/acb_modular/acb_modular_lambda.html (generated 2026-10-20).