79 lines
2.6 KiB
JavaScript
79 lines
2.6 KiB
JavaScript
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var vows = require('vows');
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var assert = require('assert');
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var suite = vows.describe('jStat.distribution');
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require('../env.js');
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var tol = 0.0000001;
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var gamma = jStat.gammafn;
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suite.addBatch({
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'weibull pdf': {
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'topic': function() {
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return jStat;
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},
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'check pdf calculation': function(jStat) {
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var pdf = jStat.weibull.pdf;
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assert.epsilon(tol, pdf(1, 1, 1), Math.exp(-1));
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assert.epsilon(tol, pdf(3, 1, 1), Math.exp(-3));
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//Scale parameter
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assert.epsilon(tol, pdf(1, 2, 1), 0.5 * Math.exp(-0.5));
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assert.epsilon(tol, pdf(1, 10, 1), 0.1 * Math.exp(-0.1));
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//Shape parameter
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assert.epsilon(tol, pdf(1, 1, 4), 4 * Math.exp(-1));
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assert.epsilon(tol, pdf(2, 1, 2), 4 * Math.exp(-4));
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//Negative test cases for invalid parameters
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assert.epsilon(tol, pdf(-1, 1, 1), 0);
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assert.epsilon(tol, pdf(1, -1, 1), 0);
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assert.epsilon(tol, pdf(1, 1, -1), 0);
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},
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'check cdf calculation': function(jStat) {
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var cdf = jStat.weibull.cdf;
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assert.epsilon(tol, cdf(1, 1, 1), 1 - Math.exp(-1));
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assert.epsilon(tol, cdf(2, 1, 1), 1 - Math.exp(-2));
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assert.epsilon(tol, cdf(1, 2, 1), 1 - Math.exp(-0.5));
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assert.epsilon(tol, cdf(2, 1, 2), 1 - Math.exp(-4));
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},
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'mean': function(jStat) {
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var mean = jStat.weibull.mean;
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assert.epsilon(tol, mean(1, 1), gamma(2));
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assert.epsilon(tol, mean(2, 1), 2 * gamma(2));
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assert.epsilon(tol, mean(1, 2), gamma(1.5));
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},
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'median': function(jStat) {
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var median = jStat.weibull.median;
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assert.epsilon(tol, median(1, 1), Math.log(2));
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assert.epsilon(tol, median(1, 2), Math.pow(Math.log(2), 0.5));
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assert.epsilon(tol, median(2, 1), 2 * Math.log(2));
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},
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'mode': function(jStat) {
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var mode = jStat.weibull.mode;
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assert.epsilon(tol, mode(1, 1), 0);
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assert.epsilon(tol, mode(1, 2), Math.pow(0.5, 0.5))
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assert.epsilon(tol, mode(3, 2), 3 * Math.pow(0.5, 0.5))
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},
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'variance': function(jStat) {
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var variance = jStat.weibull.variance;
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assert.epsilon(tol, variance(1, 1), gamma(3) - Math.pow(gamma(2), 2));
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assert.epsilon(tol, variance(1, 2), gamma(2) - Math.pow(gamma(1.5), 2));
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assert.epsilon(tol, variance(3, 2), 9 * (gamma(2) - Math.pow(gamma(1.5), 2)));
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}
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}
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});
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suite.export(module);
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