中文说明：spcl（data，nbclusters，varargin）是一种谱聚类函数，用于将随机未知数据组合成簇。在指定数据和集群数量之后，下一个参数可以根据需要变化。此函数将构造数据的完全连通相似图；
English Description：
spcl(data, nbclusters, varargin) is a spectral clustering function to assemble random unknown data into clusters. after specifying the data and the number of clusters, next parameters can vary as wanted. This function will construct the fully connected similarity graph of the data.