import { describe, expect, it } from '@jest/globals';

import { conditionNumber } from '../../src/error-analysis/condition-number.js';


describe('conditionNumber', function() {
    it('should correctly calculate the condition number for some polynomials at some points', 
    function() {
        let p1 = [
            3770986809251668.5,
            -11611163849314706,
            13622867559528270,
            -6015675011409949,
            -2535765899677980.5,
            1004670324427690,
            5119556864733271,
            -5283583821747902,
            1955103350624411,
            -252827841312240.88
        ];

        // p1 has roots at roughly (where the condition number should be high):
        //     0.3361742829036019, 
        //     0.6260997031130033 and 
        //     1.325558242403445 <- this is actually the best floating point approx. of the root

        // get condition number estimates at some points
        let c1 = conditionNumber(p1, 1.5);  // should be lowish
        let c2 = conditionNumber(p1, 1000_000_000);  // should be low
        let c3 = conditionNumber(p1, -1000_000_000);  // should be low
        let c4 = conditionNumber(p1, 0.33);  // should be pretty high ~ 10**3
        let c5 = conditionNumber(p1, 0.62609);  // should be very high ~ 10**5
        let c6 = conditionNumber(p1, 1.325558242403445);  // should be extremely high ~ 2**53
        
        //console.log(c6)

         expect(c1).toBeLessThan(250);             // => 144.87661476947537
        expect(c2).toBeLessThan(2);               // => 1.0000000061581567
        expect(c3).toBeLessThan(2);               // => 0.9999999938418433
        expect(c4).toBeGreaterThan(1000);               // => 3568.2756890558076
        expect(c5).toBeGreaterThan(1000_000);           // => 20246637.631723296
        expect(c6).toBeGreaterThan(1000_000_000_000);   // => 314905786802669100
    });
});