Frequency.cs

    public struct Frequency
    {
        private readonly long _millihertz;
        
        public double Hertz => _millihertz / 1000d;
        
        public TimeSpan Interval => TimeSpan.FromSeconds(1d / Hertz);

        public Frequency(long millihertz)
        {
            _millihertz = millihertz;
        }
        
        public static Frequency FromHertz(double hertz)
        {
            return new Frequency((long) (hertz * 1000));
        }
    }