my_d=20;
function r_from_dia(my_d) = my_d / 2;
echo("Diameter ", my_d, " is radius ", r_from_dia(my_d));
//recursion - find the sum of the values in a vector (array)
// from the start (or s'th element) to the i'th element - remember elements are
zero based
function sumv(v,i,s=0) = (i==s ? v[i] : v[i] + sumv(v,i-1,s));
vec=[ 10, 20, 30, 40 ];
echo("sum vec=", sumv(vec,2,1)); // is 20+30=50