deriv_cum_logist.m

The BNL toolbox is a set of Matlab functions for defining and estimating the parameters of a Bayesi

function d=deriv_cum_logist(x)
%computes derivative of cumulative logistic function in x

%x is row cvector or matrix and does not contain column of zeros!!

s=size(x);
%if (s(2)==1 &&s(1)>1) error('use row vectors'),end
y=exp(x)./(1+exp(x));
yy=y.^2;
v=ones(1,s(2));

e1=eye(s(2));
t1=kron(v,y-yy).*(ones(s(1),1)*e1(:)');
e2=diag(v(1:end-1),1);
t2=kron(-y+yy,v).*(ones(s(1),1)*e2(:)');
%t2=zeros(size(t1));
d=t1+t2;
d=reshape(d',[s(2) s(2) s(1)]);
d=permute(d,[2 1 3]);