import CubicRealPolynomial from "./CubicRealPolynomial.js";
import DeveloperError from "./DeveloperError.js";
import CesiumMath from "./Math.js";
import QuadraticRealPolynomial from "./QuadraticRealPolynomial.js";
/**
* Defines functions for 4th order polynomial functions of one variable with only real coefficients.
*
* @namespace QuarticRealPolynomial
*/
var QuarticRealPolynomial = {};
/**
* Provides the discriminant of the quartic equation from the supplied coefficients.
*
* @param {Number} a The coefficient of the 4th order monomial.
* @param {Number} b The coefficient of the 3rd order monomial.
* @param {Number} c The coefficient of the 2nd order monomial.
* @param {Number} d The coefficient of the 1st order monomial.
* @param {Number} e The coefficient of the 0th order monomial.
* @returns {Number} The value of the discriminant.
*/
QuarticRealPolynomial.computeDiscriminant = function (a, b, c, d, e) {
//>>includeStart('debug', pragmas.debug);
if (typeof a !== "number") {
throw new DeveloperError("a is a required number.");
}
if (typeof b !== "number") {
throw new DeveloperError("b is a required number.");
}
if (typeof c !== "number") {
throw new DeveloperError("c is a required number.");
}
if (typeof d !== "number") {
throw new DeveloperError("d is a required number.");
}
if (typeof e !== "number") {
throw new DeveloperError("e is a required number.");
}
//>>includeEnd('debug');
var a2 = a * a;
var a3 = a2 * a;
var b2 = b * b;
var b3 = b2 * b;
var c2 = c * c;
var c3 = c2 * c;
var d2 = d * d;
var d3 = d2 * d;
var e2 = e * e;
var e3 = e2 * e;
var discriminant =
b2 * c2 * d2 -
4.0 * b3 * d3 -
4.0 * a * c3 * d2 +
18 * a * b * c * d3 -
27.0 * a2 * d2 * d2 +
256.0 * a3 * e3 +
e *
(18.0 * b3 * c * d -
4.0 * b2 * c3 +
16.0 * a * c2 * c2 -
80.0 * a * b * c2 * d -
6.0 * a * b2 * d2 +
144.0 * a2 * c * d2) +
e2 *
(144.0 * a * b2 * c -
27.0 * b2 * b2 -
128.0 * a2 * c2 -
192.0 * a2 * b * d);
return discriminant;
};
function original(a3, a2, a1, a0) {
var a3Squared = a3 * a3;
var p = a2 - (3.0 * a3Squared) / 8.0;
var q = a1 - (a2 * a3) / 2.0 + (a3Squared * a3) / 8.0;
var r =
a0 -
(a1 * a3) / 4.0 +
(a2 * a3Squared) / 16.0 -
(3.0 * a3Squared * a3Squared) / 256.0;
// Find the roots of the cubic equations: h^6 + 2 p h^4 + (p^2 - 4 r) h^2 - q^2 = 0.
var cubicRoots = CubicRealPolynomial.computeRealRoots(
1.0,
2.0 * p,
p * p - 4.0 * r,
-q * q
);
if (cubicRoots.length > 0) {
var temp = -a3 / 4.0;
// Use the largest positive root.
var hSquared = cubicRoots[cubicRoots.length - 1];
if (Math.abs(hSquared) < CesiumMath.EPSILON14) {
// y^4 + p y^2 + r = 0.
var roots = QuadraticRealPolynomial.computeRealRoots(1.0, p, r);
if (roots.length === 2) {
var root0 = roots[0];
var root1 = roots[1];
var y;
if (root0 >= 0.0 && root1 >= 0.0) {
var y0 = Math.sqrt(root0);
var y1 = Math.sqrt(root1);
return [temp - y1, temp - y0, temp + y0, temp + y1];
} else if (root0 >= 0.0 && root1 < 0.0) {
y = Math.sqrt(root0);
return [temp - y, temp + y];
} else if (root0 < 0.0 && root1 >= 0.0) {
y = Math.sqrt(root1);
return [temp - y, temp + y];
}
}
return [];
} else if (hSquared > 0.0) {
var h = Math.sqrt(hSquared);
var m = (p + hSquared - q / h) / 2.0;
var n = (p + hSquared + q / h) / 2.0;
// Now solve the two quadratic factors: (y^2 + h y + m)(y^2 - h y + n);
var roots1 = QuadraticRealPolynomial.computeRealRoots(1.0, h, m);
var roots2 = QuadraticRealPolynomial.computeRealRoots(1.0, -h, n);
if (roots1.length !== 0) {
roots1[0] += temp;
roots1[1] += temp;
if (roots2.length !== 0) {
roots2[0] += temp;
roots2[1] += temp;
if (roots1[1] <= roots2[0]) {
return [roots1[0], roots1[1], roots2[0], roots2[1]];
} else if (roots2[1] <= roots1[0]) {
return [roots2[0], roots2[1], roots1[0], roots1[1]];
} else if (roots1[0] >= roots2[0] && roots1[1] <= roots2[1]) {
return [roots2[0], roots1[0], roots1[1], roots2[1]];
} else if (roots2[0] >= roots1[0] && roots2[1] <= roots1[1]) {
return [roots1[0], roots2[0], roots2[1], roots1[1]];
} else if (roots1[0] > roots2[0] && roots1[0] < roots2[1]) {
return [roots2[0], roots1[0], roots2[1], roots1[1]];
}
return [roots1[0], roots2[0], roots1[1], roots2[1]];
}
return roots1;
}
if (roots2.length !== 0) {
roots2[0] += temp;
roots2[1] += temp;
return roots2;
}
return [];
}
}
return [];
}
function neumark(a3, a2, a1, a0) {
var a1Squared = a1 * a1;
var a2Squared = a2 * a2;
var a3Squared = a3 * a3;
var p = -2.0 * a2;
var q = a1 * a3 + a2Squared - 4.0 * a0;
var r = a3Squared * a0 - a1 * a2 * a3 + a1Squared;
var cubicRoots = CubicRealPolynomial.computeRealRoots(1.0, p, q, r);
if (cubicRoots.length > 0) {
// Use the most positive root
var y = cubicRoots[0];
var temp = a2 - y;
var tempSquared = temp * temp;
var g1 = a3 / 2.0;
var h1 = temp / 2.0;
var m = tempSquared - 4.0 * a0;
var mError = tempSquared + 4.0 * Math.abs(a0);
var n = a3Squared - 4.0 * y;
var nError = a3Squared + 4.0 * Math.abs(y);
var g2;
var h2;
if (y < 0.0 || m * nError < n * mError) {
var squareRootOfN = Math.sqrt(n);
g2 = squareRootOfN / 2.0;
h2 = squareRootOfN === 0.0 ? 0.0 : (a3 * h1 - a1) / squareRootOfN;
} else {
var squareRootOfM = Math.sqrt(m);
g2 = squareRootOfM === 0.0 ? 0.0 : (a3 * h1 - a1) / squareRootOfM;
h2 = squareRootOfM / 2.0;
}
var G;
var g;
if (g1 === 0.0 && g2 === 0.0) {
G = 0.0;
g = 0.0;
} else if (CesiumMath.sign(g1) === CesiumMath.sign(g2)) {
G = g1 + g2;
g = y / G;
} else {
g = g1 - g2;
G = y / g;
}
var H;
var h;
if (h1 === 0.0 && h2 === 0.0) {
H = 0.0;
h = 0.0;
} else if (CesiumMath.sign(h1) === CesiumMath.sign(h2)) {
H = h1 + h2;
h = a0 / H;
} else {
h = h1 - h2;
H = a0 / h;
}
// Now solve the two quadratic factors: (y^2 + G y + H)(y^2 + g y + h);
var roots1 = QuadraticRealPolynomial.computeRealRoots(1.0, G, H);
var roots2 = QuadraticRealPolynomial.computeRealRoots(1.0, g, h);
if (roots1.length !== 0) {
if (roots2.length !== 0) {
if (roots1[1] <= roots2[0]) {
return [roots1[0], roots1[1], roots2[0], roots2[1]];
} else if (roots2[1] <= roots1[0]) {
return [roots2[0], roots2[1], roots1[0], roots1[1]];
} else if (roots1[0] >= roots2[0] && roots1[1] <= roots2[1]) {
return [roots2[0], roots1[0], roots1[1], roots2[1]];
} else if (roots2[0] >= roots1[0] && roots2[1] <= roots1[1]) {
return [roots1[0], roots2[0], roots2[1], roots1[1]];
} else if (roots1[0] > roots2[0] && roots1[0] < roots2[1]) {
return [roots2[0], roots1[0], roots2[1], roots1[1]];
}
return [roots1[0], roots2[0], roots1[1], roots2[1]];
}
return roots1;
}
if (roots2.length !== 0) {
return roots2;
}
}
return [];
}
/**
* Provides the real valued roots of the quartic polynomial with the provided coefficients.
*
* @param {Number} a The coefficient of the 4th order monomial.
* @param {Number} b The coefficient of the 3rd order monomial.
* @param {Number} c The coefficient of the 2nd order monomial.
* @param {Number} d The coefficient of the 1st order monomial.
* @param {Number} e The coefficient of the 0th order monomial.
* @returns {Number[]} The real valued roots.
*/
QuarticRealPolynomial.computeRealRoots = function (a, b, c, d, e) {
//>>includeStart('debug', pragmas.debug);
if (typeof a !== "number") {
throw new DeveloperError("a is a required number.");
}
if (typeof b !== "number") {
throw new DeveloperError("b is a required number.");
}
if (typeof c !== "number") {
throw new DeveloperError("c is a required number.");
}
if (typeof d !== "number") {
throw new DeveloperError("d is a required number.");
}
if (typeof e !== "number") {
throw new DeveloperError("e is a required number.");
}
//>>includeEnd('debug');
if (Math.abs(a) < CesiumMath.EPSILON15) {
return CubicRealPolynomial.computeRealRoots(b, c, d, e);
}
var a3 = b / a;
var a2 = c / a;
var a1 = d / a;
var a0 = e / a;
var k = a3 < 0.0 ? 1 : 0;
k += a2 < 0.0 ? k + 1 : k;
k += a1 < 0.0 ? k + 1 : k;
k += a0 < 0.0 ? k + 1 : k;
switch (k) {
case 0:
return original(a3, a2, a1, a0);
case 1:
return neumark(a3, a2, a1, a0);
case 2:
return neumark(a3, a2, a1, a0);
case 3:
return original(a3, a2, a1, a0);
case 4:
return original(a3, a2, a1, a0);
case 5:
return neumark(a3, a2, a1, a0);
case 6:
return original(a3, a2, a1, a0);
case 7:
return original(a3, a2, a1, a0);
case 8:
return neumark(a3, a2, a1, a0);
case 9:
return original(a3, a2, a1, a0);
case 10:
return original(a3, a2, a1, a0);
case 11:
return neumark(a3, a2, a1, a0);
case 12:
return original(a3, a2, a1, a0);
case 13:
return original(a3, a2, a1, a0);
case 14:
return original(a3, a2, a1, a0);
case 15:
return original(a3, a2, a1, a0);
default:
return undefined;
}
};
export default QuarticRealPolynomial;
