Want to turn constant parameter off in glmfit

I'm trying to fit a glm with no constant. The default behavior of glmfit includes a constant term. However, there is a 'constant' parameter for glmfit which you can turn off. I have a few questions regarding how to get this to work:

1)the constant parameter is the 5th parameter listed in the documentation (http://www.mathworks.com/help/stats/glmfit.html). Do I understand correctly that there is no way to skip prior parameters, so I must enter something for the previous 4 parameters?

2)If I do need to enter things for all previous parameters, what am I supposed to put in for 'offset' and 'weights'? The documentation doesn't specify what the default parameters are.