how to predict when model rules are converted to a matrix

Hi every body I'm trying to implement a genetic algorithm on a decision tree, for my master thesis. First, I decide to convert the obtained decision tree in R to a matrix manually (it's a time consuming task cause I couldn't find a function to do this in R or Matlab) while each row of this matrix represents a rule of the tree. Now the question is that how I can use this matrix to predict accuracy of built model (Decision tree)through a new data? Is there any function to do this action in matlab?

Many thank for any response,