The general solutions for the harmonic oscillator differential equation fall into four general categories: 1) Undamped: [math]x(t) = Ae^{i\omega t}[/math] This is a free-running sinusoidal oscillation that doesn't change over time.
Key Facts. 1  Itâs normal to have mild cramps during your period. 2  Menstrual cramps often start 1-2 days after your period begins. 3  If your cramps donât get better with over-the-counter medicine, you should see your health care provider.
Why menstrual cramps happen. Itâs common to feel discomfort around your abdomen, lower back, and thighs when youâre menstruating. During your period, the muscles of your womb contract and relax to help shed built-up lining. Sometimes youâll experience cramps, which are your muscles at work.