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

Pure JavaScript game engine. Fully featured and production ready.

/**
 * Adds polynomial `a` into `target` in place.
 *
 *   target(x) := target(x) + a(x)
 *
 * Coefficient layout: index i is the coefficient of x^i (ascending). If
 * `a_len > target_len`, the excess coefficients in `target` at indices
 * [target_len, a_len) are first cleared to zero, so the returned length
 * (max of the two input lengths) reflects valid coefficients.
 *
 * @param {number[]|Float64Array|Float32Array} target receives the sum, length >= max(target_len, a_len)
 * @param {number} target_len current number of coefficients in target
 * @param {number[]|Float64Array|Float32Array} a
 * @param {number} a_len number of coefficients in a
 * @returns {number} new logical length of target = max(target_len, a_len)
 */
export function polynomial_add_into(target, target_len, a, a_len) {
    const n = a_len > target_len ? a_len : target_len;

    for (let i = target_len; i < n; i++) {
        target[i] = 0;
    }

    for (let i = 0; i < a_len; i++) {
        target[i] += a[i];
    }

    return n;
}