How can I plot my function?

I am trying to use Matlab but I don't remember basic functions. Could anyone help why Matlab couldn't plot this code?

for n=1:20
for i=-1000:1000
x=i/1000;
u=(((2*(-1)^n))/(n*pi))*((6/((n^2*pi^2)^3))-1)*sin(n*pi*x);
hold on
plot (x,u);
end
end

Answer 1

[Walter Roberson]

You are plotting with scalar u and scalar x. Remember that you need to plot() with at least two adjacent real-valued coordinates in a single call in order for MATLAB to draw a line.

for n=1:20
  i=-1000:1000;
  x=i/1000;
  u = (((2*(-1)^n))/(n*pi))*((6/((n^2*pi^2)^3))-1)*sin(n*pi*x);
  hold on
  plot (x,u, '-*');
end

Answer 2

[David Hill]

hold on
i=-1000:1000;
x=i/1000;
for n=1:20
  u=(((2*(-1)^n))/(n*pi))*((6/((n^2*pi^2)^3))-1)*sin(n*pi*x);
  plot(x,u);
end