（填空题）已知函数\(f(x)=\begin{cases}0, & 0\leq x\lt\frac{1}{2} \\ x^2, & \frac{1}{2}\leq x\leq1 \end{cases}\)的傅里叶级数为\(\sum_{n = 1}^{\infty}b_n\sin n\pi x\)，\(S(x)\)为\(\sum_{n = 1}^{\infty}b_n\sin n\pi x\)的和函数，则\(S\left(-\frac{7}{2}\right)=\)______．