MATLAB: Plotting trouble

plot

can anyone help me see what im doing wrong here i want to plot this with a for loop
for i=1:20
x= i
y=x
end
plot(x,y)
but when i plot it,there is no graph in the figure window and the graph has a really weird range that i didnt input however when i try this it works just fine why is that
x=1:1:20
y=x
plot(x,y)

Best Answer

In your for-loop, x and y are assigned a value one at a time. x and y are always over-written. So at the end of the loop, you end up with x==20 and y==20. The plot just shows one dot.
In the second approach, x is a vector and so is y.