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x/simplestatistics/test/poisson_distribution.test.js

simple statistics for node & browser javascript
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/* eslint no-shadow: 0 */
const test = require("tap").test;const ss = require("../dist/simple-statistics.js");
function rnd(n) { return parseFloat(n.toFixed(4));}
// expected cumulative probabilities taken from Appendix 1, Table I of William W. Hines & Douglas C.// Montgomery, "Probability and Statistics in Engineering and Management Science", Wiley (1980).test("poissonDistribution", function (t) { t.test( "can return generate probability and cumulative probability distributions for lambda = 3.0", function (t) { t.equal("object", typeof ss.poissonDistribution(3.0)); t.equal(rnd(ss.poissonDistribution(3.0)[3]), 0.224, ss.epsilon); t.end(); } ); t.test( "can generate probability and cumulative probability distributions for lambda = 4.0", function (t) { t.equal("object", typeof ss.poissonDistribution(4.0)); t.equal(rnd(ss.poissonDistribution(4.0)[2]), 0.1465, ss.epsilon); t.end(); } ); t.test( "can generate probability and cumulative probability distributions for lambda = 5.5", function (t) { t.equal("object", typeof ss.poissonDistribution(5.5)); t.equal(rnd(ss.poissonDistribution(5.5)[7]), 0.1234, ss.epsilon); t.end(); } ); t.test( "can generate probability and cumulative probability distributions for lambda = 9.5", function (t) { t.equal("object", typeof ss.poissonDistribution(9.5)); t.equal(rnd(ss.poissonDistribution(9.5)[17]), 0.0088, ss.epsilon); t.end(); } ); t.test("can return undefined when lambda <= 0", function (t) { t.equal(undefined, ss.poissonDistribution(0)); t.equal(undefined, ss.poissonDistribution(-10)); t.end(); }); t.end();});