function [s,term] = expF(x);
        if (x == 0), s = 1; return; end
        t = 1;
        s = t;
        x1 = abs(x);
        term = [];

        j = 1;
        while (t > s*eps),
                t = t*(x1/j);
                s = s + t;
                j = j+1;
                term = [term ; t];
        end
        if (x < 0), s = 1/s; end