17 lines
419 B
JavaScript
17 lines
419 B
JavaScript
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import {HALF_PI} from '../constants/values';
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export default function(eccent, phi, sinphi) {
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if (Math.abs(phi) > HALF_PI) {
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return Number.NaN;
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}
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if (phi === HALF_PI) {
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return Number.POSITIVE_INFINITY;
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}
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if (phi === -1 * HALF_PI) {
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return Number.NEGATIVE_INFINITY;
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}
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var con = eccent * sinphi;
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return Math.log(Math.tan((HALF_PI + phi) / 2)) + eccent * Math.log((1 - con) / (1 + con)) / 2;
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}
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