LagrangePolynomialApproximationSpec.js

/*global defineSuite*/
defineSuite([
        'Core/LagrangePolynomialApproximation'
    ], function(
        LagrangePolynomialApproximation) {
    "use strict";
    /*global jasmine,describe,xdescribe,it,xit,expect,beforeEach,afterEach,beforeAll,afterAll,spyOn*/

    //The results of these specs were validated against STK Components
    //an aerospace SDK available from Analytical Graphics. www.agi.com/components/

    var xTable = [0, 60, 120, 180, 240, 300, 360, 420];
    var yTable = [
                  13378137.0000000, 0.000000000, 0,
                  13374128.3576279, 327475.593690065, 0,
                  13362104.8328212, 654754.936954423, 0,
                  13342073.6310691, 981641.896976832, 0,
                  13314046.7567223, 1307940.576089510, 0,
                  13278041.0057990, 1633455.429171170, 0,
                  13234077.9559193, 1957991.380833850, 0,
                  13182183.9533740, 2281353.942328160, 0
                 ];

    var x = 100.0;

    it('interpolation produces correct results.', function() {
        var result = LagrangePolynomialApproximation.interpolateOrderZero(x, xTable, yTable, 3);
        var expectedResult = [13367002.870928623, 545695.7388100647, 0];
        expect(result).toEqualEpsilon(expectedResult, 1e-15);
    });

    it('interpolation produces correct results with a result parameter', function() {
        var result = new Array(3);
        var returnedResult = LagrangePolynomialApproximation.interpolateOrderZero(x, xTable, yTable, 3, result);
        var expectedResult = [13367002.870928623, 545695.7388100647, 0];
        expect(result).toBe(returnedResult);
        expect(result).toEqualEpsilon(expectedResult, 1e-15);
    });

    it('getRequiredDataPoints should be 1 more than degree, except for 0, which requires 2', function() {
        expect(LagrangePolynomialApproximation.getRequiredDataPoints(0)).toEqual(2);
        expect(LagrangePolynomialApproximation.getRequiredDataPoints(1)).toEqual(2);
        expect(LagrangePolynomialApproximation.getRequiredDataPoints(2)).toEqual(3);
        expect(LagrangePolynomialApproximation.getRequiredDataPoints(3)).toEqual(4);
    });
});