Complete Elliptic Integrals Calculator
Free online complete elliptic integrals calculator. Enter your values and get instant results with the formula, step-by-step working, a worked example and FAQs — everything runs locally in your browser on Calcton, no signup required.
中文版：完全椭圆积分在线计算器
完全椭圆积分 K(m) = ∫₀^(π/2) dθ/√(1 − m sin²θ) 与 E(m) = ∫₀^(π/2) √(1 − m sin²θ) dθ 是 19 世纪分析学的枢纽对象：单摆的真实周期、椭圆的真实周长、弹性力学与共形映射都依赖它们。Legendre 为此建立了一整套模函数理论，Gauss 的算术几何平均 AGM 与 K 以 π/(2·AGM) 相连。
实现采用直接积分（Simpson 20000 段）：在 m ∈ [0, 1) 全域稳健，避开近 m = 1 时 AGM 迭代需要额外渐近修正的坑。锚点：m = 0.5（m = 1/2 是「(sin 45°)² 摆」，K 值与权威表一致到 1e-10）、m = 0（K = E = π/2）、m = 1（E = 1 特判、K 发散）、m = 0.9 与高斯交叉验证一致。
参考值
K(0.5) = 1.8540746773013719，E(0.5) = 1.3506438810476758
K(0) = E(0) = π/2 = 1.5707963267948966，E(1) = 1，K(1) = ∞
K(0.9) = 2.5780921133481735（近奇异区的 60% 放大来自被积函数在 θ = 90° 的尖峰）
How to use the Complete Elliptic Integrals Calculator
- Fill in the inputs with your own numbers — every field shows what it expects.
- The result updates instantly as you type; no "Calculate" click needed.
- Read the result card for the main figure, the step-by-step formula, and practical notes.
Frequently asked questions
Is the Complete Elliptic Integrals Calculator free?
Yes — all math calculators on Calcton are free, with no sign-up required. Your inputs are processed in your browser and never sent to a server.
Is there a Chinese version of this tool?
Yes. Use the Chinese version link above — it is the same calculator with the interface in Simplified Chinese.
References
Formulas and benchmarks used by this calculator follow these published sources.
KevinContent LeadCalcton Editorial Team · Last updated 2026-09-28
Kevin maintains Calcton's formula verification and content: every calculator cites the standard it implements, worked examples are recomputed programmatically, and health benchmarks follow WHO and international guidelines.
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