$\begin{cases}\frac{(459-576)t}{180}+576 & \text{if $(t\ge 0)\land (t\le 180)$}\\ \frac{(406-459)(t-180)}{180}+459 & \text{if $(t> 180)\land (t\le 360)$}\\ \frac{(377-406)(t-360)}{180}+406 & \text{if $(t> 360)\land (t\le 540)$}\\ \frac{(348-377)(t-540)}{180}+377 & \text{if $(t> 540)\land (t\le 720)$}\\ \frac{(336-348)(t-720)}{180}+348 & \text{if $(t> 720)\land (t\le 900)$}\\ \frac{(334-336)(t-900)}{180}+336 & \text{if $(t> 900)\land (t\le 1080)$}\\ 334 & \text{if $(t> 1080)\land (t\le \mathrm{stimEnd})$}\\ 60 & \text{otherwise}\end{cases}$