fmincon, how does interior point restrict parameters

I used my own restriction transformation inside the function to allow fmincon to searh globally. However i ran into nummerical troubles, so instead of doing it my own way i just used Matlabs built in way of restricting paramaters which worked fine. Now i know that my method also works, but apparantly it is less robust to nummerical errors. Does any one know how Matlab restricts the parameters ?

          options = optimset('TolX',1e-3,'Algorithm','interior-point'); 
          options = optimset(options,'MaxFunEvals',1000,'Display','off');       
          [p,~,~]= fmincon(@(p) -likelihoodFunktion(p, vY, iN, type),p0, [],[],[],[],[-0.995 0.00000001 -Inf],[0.995 2 Inf],[],options);

The above is my code i ended up using. It works fine, it just bugs me i dont know how Matlab is doing it.

Answer 1

[Matt J]

See equation (6-51) at

http://www.mathworks.com/help/optim/ug/constrained-nonlinear-optimization-algorithms.html#brnpd5f

Answer 2

[DoVile Last Name:]

Thank you