posdef.m

建立routh阵列表的函数

function [key,sdet]=posdef(A)
[nr,nc]=size(A); sdet=[];
for i=1:nr
   sdet=[sdet,det(A(1:i,1:i))];
end
key=0;
if any(sdet<0), key=-1;
else any(sdet>0),key=1;
end