how to generate code?

n = 3; ri=0.9;lamda=0.7;
config = dec2bin(0:2.^L-1)-'0';
nl = sum(config,2);
nu = n-nl;
P  = lamda.^nl .* (1-lamda).^nu;
nodeRel(1:n)=ri;

i want two terminal reliability. i consider 3 nodes (i.e., 1,2,3),this is fixed network. 1 is source node,3 is destination node and 2 is intermediate node. the shortest path is 1 to 3, because fixed network 1 is source and 3 is destination. then,

2TR = ri^m

where m is limit on intermediate node.

i need this output

2TR = 0.9 *0.9=0.81

please help me to generate this 2 terminal reliability.