有木有人能帮忙解决我的难题？求好心人！！！

trace is the trace of the covariance matrix or the total variance.  Difference is the difference between the eigenvalues (component1 eigenvalue - component2 eigenvalue, and so on). unexplained is the unexplained variances caused by omitting the other components.  You may want to read the principle component section to get better idea as what it does and what the results mean.

谢谢您的帮忙，但是“trace is the trace of the covariance matrix or the total variance”这句话能麻烦您翻译一下吗？这里的trace是踪迹的意思，踪迹是协方差或者是方差的踪迹，我翻译成这样，应该不对吧？

suppose the covariance matrix is (3,2\2,4), the trace is 3+4=7.  This is also the total variance: if you sum the variances of the variables "trunk weight length headroom", it is the same as the number in trace.

原来是这样，谢谢您！