function conjugate$1(out, a) {
    out[0] = -a[0];
    out[1] = -a[1];
    out[2] = -a[2];
    out[3] = a[3];
    return out;
  }
Calculates the conjugate of a quat
If the quaternion is normalized, this function is faster than quat.inverse and produces the same result.

@param {quat} out the receiving quaternion
@param {ReadonlyQuat} a quat to calculate conjugate of
@returns {quat} out