function [x, dx, g, f_num]=indef_integral_sp(a, b, N)

x=linspace(a,b,N); dx=x(2)-x(1);
il=(1:1:N-1); ir=(2:1:N);
g(1)=1;
g(ir)=sin(x(ir))./x(ir);

f_num(1)=0
trap=dx*(g(il)+g(ir))/2;
f_num(ir)=cumsum(trap);

end
