matlab的S变换
时频变换工具箱中‘st’函数中%function [st,t,f] = st(timeseries,minfreq,maxfreq,samplingrate,freqsamplingrate)，其中最大频率maxfreq是根据什么决定的？maxfreq取fs/2感觉不对，是该取N/2吗？N为采样点数。
有知道该如何取值的吗，还有samplingrate,freqsamplingrate是默认即可吗？当输入信号过长时，会因st矩阵过大而显示无法计算，这时要改变频率分辨率应该修改哪个参数呢？
% Optional Inputs
%
%"minfreq" is the minimum frequency in the ST result(Default=0)
%"maxfreq" is the maximum frequency in the ST result (Default=Nyquist)
%"samplingrate" is the time interval between samples (Default=1)
%"freqsamplingrate" is the frequency-sampling interval you desire in the ST result (Default=1)
%Passing a negative number will give the default ex. [s,t,f] = st(data,-1,-1,2,2)
希望有人能答疑解惑一下，谢谢！
