How to change cost in matlab function.

I am using A_Star_Search algorithm for finding shortest distance but i want to give cost for left =2 and simple cost is =1 . so that it prefers to go forward rather than left or right.

link where i am getting code. http://in.mathworks.com/matlabcentral/fileexchange/44215-an-implementation-of-a-star-search-algorithm-for-grid-search