function approxcapacity=evalcapacity(moms,rho,K,numterms)

    approxcapacity = 0;
    for (k=1:numterms)
      intermediatesum = (-K)^k;
      for (r=1:k)
        intermediatesum = intermediatesum + mfun('binomial',k,r)*moms(r)*(-K)^(k-r);
      end
      approxcapacity = approxcapacity + (-1)^(k+1)*rho^k*intermediatesum/(k*(1+K*rho)^k);
    end
    approxcapacity = approxcapacity/log(2);