sequence c = repeat(0,12)

function gamma(atom z)
    atom accm = c[1]
    if accm=0 then
        accm = sqrt(2*PI)
        c[1] = accm
        atom k1_factrl = 1  -- (k - 1)!*(-1)^k with 0!==1
        for k=2 to 12 do
            c[k] = exp(13-k)*power(13-k,k-1.5)/k1_factrl
            k1_factrl *= -(k-1)
        end for
    end if
    for k=2 to 12 do
        accm += c[k]/(z+k-1)
    end for
    accm *= exp(-(z+12))*power(z+12,z+0.5) -- Gamma(z+1)
    return accm/z
end function

procedure sq(atom x, atom mul)
atom p = x*mul
    printf(1,"%18.16g,%18.15g\n",{x,p*p})
end procedure

procedure si(atom x)
    printf(1,"%18.15f\n",{x})
end procedure

sq(gamma(-3/2),3/4)
sq(gamma(-1/2),-1/2)
sq(gamma(1/2),1)
si(gamma(1))
sq(gamma(3/2),2)
si(gamma(2))
sq(gamma(5/2),4/3)
si(gamma(3))
sq(gamma(7/2),8/15)
si(gamma(4))