33 lines
909 B
JavaScript
33 lines
909 B
JavaScript
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import {HALF_PI} from '../constants/values';
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export default function(eccent, q) {
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var temp = 1 - (1 - eccent * eccent) / (2 * eccent) * Math.log((1 - eccent) / (1 + eccent));
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if (Math.abs(Math.abs(q) - temp) < 1.0E-6) {
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if (q < 0) {
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return (-1 * HALF_PI);
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}
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else {
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return HALF_PI;
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}
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}
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//var phi = 0.5* q/(1-eccent*eccent);
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var phi = Math.asin(0.5 * q);
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var dphi;
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var sin_phi;
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var cos_phi;
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var con;
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for (var i = 0; i < 30; i++) {
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sin_phi = Math.sin(phi);
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cos_phi = Math.cos(phi);
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con = eccent * sin_phi;
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dphi = Math.pow(1 - con * con, 2) / (2 * cos_phi) * (q / (1 - eccent * eccent) - sin_phi / (1 - con * con) + 0.5 / eccent * Math.log((1 - con) / (1 + con)));
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phi += dphi;
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if (Math.abs(dphi) <= 0.0000000001) {
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return phi;
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}
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}
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//console.log("IQSFN-CONV:Latitude failed to converge after 30 iterations");
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return NaN;
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}
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