cum_logit.m

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

function y=cum_logit(x)
%every column of x is prob vector of size k, y is cumulative logit of length k-1
%if only one prob vector, use row vector!



if isvector(x)
     if (size(x,2)==1), error('sum of rows =1, input should be row vector! ');,return,end;
end
d=ndims(x);
if d>2 error('cum_logit only defined for vectors and matrices'),return,end;
if prod(sum(x,d))<.999 | prod(sum(x,d))>1.001 error('one of the x is not a probability vector, sum(x)~=1');,return,end;

for i=2:size(x,2)
    y(:,i-1)=log(sum(x(:,i:end),2)./sum(x(:,1:i-1),2));
end