@woosh/meep-engine/src/core/math/linalg/polynomial_cubic_derivative_eval.js

Pure JavaScript game engine. Fully featured and production ready.

/**
 * Evaluates p'(x), the first derivative of the cubic stored at
 * coeffs[base..base+3]:
 *
 *   p'(x) = coeffs[base+1]
 *         + 2 * coeffs[base+2] * x
 *         + 3 * coeffs[base+3] * x^2
 *
 * @param {number[]|Float32Array|Float64Array} coeffs
 * @param {number} base index of the constant term (coefficient of x^0)
 * @param {number} x
 * @returns {number}
 */
export function polynomial_cubic_derivative_eval(coeffs, base, x) {
    return coeffs[base + 1] + x * (2 * coeffs[base + 2] + x * 3 * coeffs[base + 3]);
}