Templated Matrix class

[Andrew Spott]

So, I'm trying to create a matrix class that is templated, but I don't really 
understand templates, so I don't know why this doesn't work.  Any idea why I 
can't seem to do 2-D arrays?

-Andrew

module matrix;
private import std.string;

class Matrix(T) {
        private:
        T[][] ma;
        int nn;
        

        public:

        this() {
        }

        this(int n, int m) {
                ma[] = new T[m];
                ma = new T[n][m];
        }

        this(int n, int m, T a) {
                ma = new T[n][m];
                ma[][] = a;
        }

        T opIndex(int n, int m) {
                return ma[n][m];
        }

        void opIndexAssign(T)(T a, int n, int m) {
                ma[n][m] = a;
        }

        int rows() {
                return ma.length;
        }

        int cols() {
                return ma[].length;
        }

        string toString() {
                if (ma.length == 0) return "[]";
                foreach (h; ma[0..$-1]) {
                        string s = "[";
                        foreach (k; h[0..$-1]) {
                                s = std.string.format("%s, %s", s, k);
                        }
                        s = std.string.format("%s, %s]\n", s, h[$-1]);
    }
                return s;
        }

}