matlab求fisher信息,matlab求解fisher 信息矩阵
现在要求置信区间，需要用fisher information matrix，其中，如果有三个变量，其表达形式如图所示，其中分子的那个符号是极大似然函数。
现在如何求得这个矩阵
本来写了一个m文件，用的是符号函数，但是现在看来对符号函数理解有误
但是现在令f输出，输出f = 0?而不是一个表达式
%This scripits try to find out the FIM-fisher information matrix
syms a b c d e
global S1o_f2 S2o_f2 S3o_f2 S4o_f2 S5o_f2 S6o_f2; %这些数据通过另一个文件读入
n1 = length(S1o_f2);
n2 = length(S2o_f2);
n3 = length(S3o_f2);
n4 = length(S4o_f2);
n5 = length(S5o_f2);
n6 = length(S6o_f2);
f1 =0;f2 =0;f3 =0;f4 =0;f5 =0;f6 =0;
T1 = 353.15;RH1 = 80; I1 = 60;
T2 = 343.15;RH2 = 95; I2 = 40;
T3 = 328.15;RH3 = 80; I3 = 40;
T4 = 353.15;RH4 = 80; I4 = 20;
T5 = 343.15;RH5 = 95; I5 = 60;
T6 = 328.15;RH6 = 95; I6 = 20;
for i = 1:n1
f1 = f1+(log(e)+(e-1).*log(S1o_f2(i,1))-e*(a+b/T1+c/RH1+d*log(I1))-(S1o_f2(i,1).^e)*exp(-e*(a+b/T1+c/RH1+d*log(I1)))); %后来发现可
%以用矩阵计算，但是没有改
end
for i = 1:n2
f2 = f2+(log(e)+(e-1).*log(S2o_f2(i,1))-e*(a+b/T2+c/RH2+d*log(I2))-(S2o_f2(i,1).^e)*exp(-e*(a+b/T2+c/RH2+d*log(I2))));
end
for i = 1:n3
f3 = f3+(log(e)+(e-1).*log(S3o_f2(i,1))-e*(a+b/T3+c/RH3+d*log(I3))-(S3o_f2(i,1).^e)*exp(-e*(a+b/T3+c/RH3+d*log(I3))));
end
for i = 1:n4
f4 = f4+(log(e)+(e-1).*log(S4o_f2(i,1))-e*(a+b/T4+c/RH4+d*log(I4))-(S4o_f2(i,1).^e)*exp(-e*(a+b/T4+c/RH4+d*log(I4))));
end
for i = 1:n5
f5 = f5+(log(e)+(e-1).*log(S5o_f2(i,1))-e*(a+b/T5+c/RH5+d*log(I5))-(S5o_f2(i,1).^e)*exp(-e*(a+b/T5+c/RH5+d*log(I5))));
end
for i = 1:n6
f6 = f6+(log(e)+(e-1).*log(S6o_f2(i,1))-e*(a+b/T6+c/RH6+d*log(I6))-(S6o_f2(i,1).^e)*exp(-e*(a+b/T6+c/RH6+d*log(I6))));
end
f = -(f1+f2+f3+f4+f5+f6)
dfd1 = diff(f,a);
dfd2 = diff(f,b);
dfd3 = diff(f,c);
dfd4 = diff(f,d);
dfd5 = diff(f,e);
dfd1d1 = diff(dfd1,a);
dfd1d2 = diff(dfd1,b);
dfd1d3 = diff(dfd1,c);
dfd1d4 = diff(dfd1,d);
dfd1d5 = diff(dfd1,e);
dfd2d2 = diff(dfd2,b);
dfd2d3 = diff(dfd2,c);
dfd2d4 = diff(dfd2,d);
dfd2d5 = diff(dfd2,e);
dfd3d3 = diff(dfd3,c);
dfd3d4 = diff(dfd3,d);
dfd3d5 = diff(dfd3,e);
dfd4d4 = diff(dfd4,d);
dfd4d5 = diff(dfd4,e);
dfd5d5 = diff(dfd5,e);
F = zeros(5,5);
F(1,1) = subs(dfd1d1,[a b c d e],O); %O是一个(1，5)的数值矩阵
F(1,2) = subs(dfd1d2,[a b c d e],O);
F(1,3) = subs(dfd1d3,[a b c d e],O);
F(1,4) = subs(dfd1d4,[a b c d e],O);
F(1,5) = subs(dfd1d5,[a b c d e],O);
F(2,2) = subs(dfd2d2,[a b c d e],O);
F(2,3) = subs(dfd2d3,[a b c d e],O);
F(2,4) = subs(dfd2d4,[a b c d e],O);
F(2,5) = subs(dfd2d5,[a b c d e],O);
F(3,3) = subs(dfd3d3,[a b c d e],O);
F(3,4) = subs(dfd3d4,[a b c d e],O);
F(3,5) = subs(dfd3d5,[a b c d e],O);
F(4,4) = subs(dfd4d4,[a b c d e],O);
F(4,5) = subs(dfd4d5,[a b c d e],O);
F(5,5) = subs(dfd5d5,[a b c d e],O);
F(2,1) = F(1,2);
F(3,1) = F(1,3);
F(3,2) = F(2,3);
F(4,1) = F(1,4);
F(4,2) = F(2,4);
F(4,3) = F(3,4);
F(5,1) = F(1,5);
F(5,2) = F(2,5);
F(5,3) = F(3,5);
F(5,4) = F(4,5);
fisher informationg matrix.jpg