32 lines
1.6 KiB
JavaScript
32 lines
1.6 KiB
JavaScript
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var test = require('tape');
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var ss = require('../');
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function rnd(n) {
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return parseFloat(n.toFixed(4));
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}
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test('binomial_distribution', function(t) {
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// Data given in the [Wikipedia example](http://en.wikipedia.org/wiki/Binomial_distribution#Example) retrieved 29 Mar 2014
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// Cumulative probabilities worked by hand to mitigate accumulated rounding errors.
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test('can return generate probability and cumulative probability distributions for n = 6, p = 0.3', function(t) {
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t.equal('object', typeof ss.binomial_distribution(6, 0.3));
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t.equal(rnd(ss.binomial_distribution(6, 0.3)[0]), 0.1176, ss.epsilon);
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t.equal(rnd(ss.binomial_distribution(6, 0.3)[1]), 0.3025, ss.epsilon);
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t.equal(rnd(ss.binomial_distribution(6, 0.3)[2]), 0.3241, ss.epsilon);
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t.equal(rnd(ss.binomial_distribution(6, 0.3)[3]), 0.1852, ss.epsilon);
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t.equal(rnd(ss.binomial_distribution(6, 0.3)[4]), 0.0595, ss.epsilon);
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t.equal(rnd(ss.binomial_distribution(6, 0.3)[5]), 0.0102, ss.epsilon);
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t.equal(rnd(ss.binomial_distribution(6, 0.3)[6]), 0.0007, ss.epsilon);
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t.end();
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});
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test('can return null when p or n are not valid parameters', function(t) {
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t.equal(null, ss.binomial_distribution(0, 0.5), 'n should be strictly positive');
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t.equal(null, ss.binomial_distribution(1.5, 0.5), 'n should be an integer');
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t.equal(null, ss.binomial_distribution(2, -0.01), 'p should be greater than 0.0');
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t.equal(null, ss.binomial_distribution(2, 1.5), 'p should be less than 1.0');
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t.end();
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});
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t.end();
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});
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