Your y in the ocde is a anonymous function:
function_handle with value:
@(x)sin(x)
You need to input some value into it....Like
y(1), y(2), y(pi) etc...
You cannot use sum(y) straight away.
May be you have to repalce this line:
monte_carlo=c*(sum(y)/h(i));
with
monte_carlo=c*(sum(y(x(1:i)))/h);
