说明：  MATLAB实现连续信号采样、频谱分析和采样信号恢复的方法。计算在临界采样、过采样、欠采样三种不同条件下恢复信号的误差，并由此总结采样频率对信号恢复产生误差的影响，从而验证时域采样定理。
(MATLAB continuous signal sampling, spectral analysis and sampling signal recovery method. Calculated in a critical sampling, the oversampling signal error recovery due to the sampling of the three different conditions, and thereby generate error summarizes the sampling frequency for signal recovery, in order to verify the time domain sampling theorem.)