import { factory } from '../../utils/factory.js'; var name = 'polynomialRoot'; var dependencies = ['typed', 'isZero', 'equalScalar', 'add', 'subtract', 'multiply', 'divide', 'sqrt', 'unaryMinus', 'cbrt', 'typeOf', 'im', 're']; export var createPolynomialRoot = /* #__PURE__ */factory(name, dependencies, _ref => { var { typed, isZero, equalScalar, add, subtract, multiply, divide, sqrt, unaryMinus, cbrt, typeOf, im, re } = _ref; /** * Finds the numerical values of the distinct roots of a polynomial with real or complex coefficients. * Currently operates only on linear, quadratic, and cubic polynomials using the standard * formulas for the roots. * * Syntax: * * math.polynomialRoot(constant, linearCoeff, quadraticCoeff, cubicCoeff) * * Examples: * // linear * math.polynomialRoot(6, 3) // [-2] * math.polynomialRoot(math.complex(6,3), 3) // [-2 - i] * math.polynomialRoot(math.complex(6,3), math.complex(2,1)) // [-3 + 0i] * // quadratic * math.polynomialRoot(2, -3, 1) // [2, 1] * math.polynomialRoot(8, 8, 2) // [-2] * math.polynomialRoot(-2, 0, 1) // [1.4142135623730951, -1.4142135623730951] * math.polynomialRoot(2, -2, 1) // [1 + i, 1 - i] * math.polynomialRoot(math.complex(1,3), math.complex(-3, -2), 1) // [2 + i, 1 + i] * // cubic * math.polynomialRoot(-6, 11, -6, 1) // [1, 3, 2] * math.polynomialRoot(-8, 0, 0, 1) // [-1 - 1.7320508075688774i, 2, -1 + 1.7320508075688774i] * math.polynomialRoot(0, 8, 8, 2) // [0, -2] * math.polynomialRoot(1, 1, 1, 1) // [-1 + 0i, 0 - i, 0 + i] * * See also: * cbrt, sqrt * * @param {... number | Complex} coeffs * The coefficients of the polynomial, starting with with the constant coefficent, followed * by the linear coefficient and subsequent coefficients of increasing powers. * @return {Array} The distinct roots of the polynomial */ return typed(name, { 'number|Complex, ...number|Complex': (constant, restCoeffs) => { var coeffs = [constant, ...restCoeffs]; while (coeffs.length > 0 && isZero(coeffs[coeffs.length - 1])) { coeffs.pop(); } if (coeffs.length < 2) { throw new RangeError("Polynomial [".concat(constant, ", ").concat(restCoeffs, "] must have a non-zero non-constant coefficient")); } switch (coeffs.length) { case 2: // linear return [unaryMinus(divide(coeffs[0], coeffs[1]))]; case 3: { // quadratic var [c, b, a] = coeffs; var denom = multiply(2, a); var d1 = multiply(b, b); var d2 = multiply(4, a, c); if (equalScalar(d1, d2)) return [divide(unaryMinus(b), denom)]; var discriminant = sqrt(subtract(d1, d2)); return [divide(subtract(discriminant, b), denom), divide(subtract(unaryMinus(discriminant), b), denom)]; } case 4: { // cubic, cf. https://en.wikipedia.org/wiki/Cubic_equation var [d, _c, _b, _a] = coeffs; var _denom = unaryMinus(multiply(3, _a)); var D0_1 = multiply(_b, _b); var D0_2 = multiply(3, _a, _c); var D1_1 = add(multiply(2, _b, _b, _b), multiply(27, _a, _a, d)); var D1_2 = multiply(9, _a, _b, _c); if (equalScalar(D0_1, D0_2) && equalScalar(D1_1, D1_2)) { return [divide(_b, _denom)]; } var Delta0 = subtract(D0_1, D0_2); var Delta1 = subtract(D1_1, D1_2); var discriminant1 = add(multiply(18, _a, _b, _c, d), multiply(_b, _b, _c, _c)); var discriminant2 = add(multiply(4, _b, _b, _b, d), multiply(4, _a, _c, _c, _c), multiply(27, _a, _a, d, d)); if (equalScalar(discriminant1, discriminant2)) { return [divide(subtract(multiply(4, _a, _b, _c), add(multiply(9, _a, _a, d), multiply(_b, _b, _b))), multiply(_a, Delta0)), // simple root divide(subtract(multiply(9, _a, d), multiply(_b, _c)), multiply(2, Delta0)) // double root ]; } // OK, we have three distinct roots var Ccubed; if (equalScalar(D0_1, D0_2)) { Ccubed = Delta1; } else { Ccubed = divide(add(Delta1, sqrt(subtract(multiply(Delta1, Delta1), multiply(4, Delta0, Delta0, Delta0)))), 2); } var allRoots = true; var rawRoots = cbrt(Ccubed, allRoots).toArray().map(C => divide(add(_b, C, divide(Delta0, C)), _denom)); return rawRoots.map(r => { if (typeOf(r) === 'Complex' && equalScalar(re(r), re(r) + im(r))) { return re(r); } return r; }); } default: throw new RangeError("only implemented for cubic or lower-order polynomials, not ".concat(coeffs)); } } }); });