From f0fd57d43b87694c409456f5f0c209da2ea40d1e Mon Sep 17 00:00:00 2001 From: Jason Davies Date: Thu, 14 Feb 2013 09:53:28 +0000 Subject: [PATCH] Simplify d3.geo.vanDerGrinten3. --- geo/projection/van-der-grinten3.js | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/geo/projection/van-der-grinten3.js b/geo/projection/van-der-grinten3.js index 5fbc562..3cbd48c 100644 --- a/geo/projection/van-der-grinten3.js +++ b/geo/projection/van-der-grinten3.js @@ -1,13 +1,13 @@ function vanDerGrinten3(λ, φ) { if (Math.abs(φ) < ε) return [λ, 0]; - var sinθ = Math.abs(2 * φ / π), + var sinθ = 2 * φ / π, θ = asin(sinθ); - if (Math.abs(λ) < ε || Math.abs(Math.abs(φ) - π / 2) < ε) return [0, sgn(φ) * π * Math.tan(θ / 2)]; - var A = Math.abs(π / λ - λ / π) / 2, + if (Math.abs(λ) < ε || Math.abs(Math.abs(φ) - π / 2) < ε) return [0, π * Math.tan(θ / 2)]; + var A = (π / λ - λ / π) / 2, y1 = sinθ / (1 + Math.cos(θ)); return [ - sgn(λ) * π * (asqrt(A * A + 1 - y1 * y1) - A), - sgn(φ) * π * y1 + π * (sgn(λ) * asqrt(A * A + 1 - y1 * y1) - A), + π * y1 ]; }