Plotting a position function - Help!

I am asked to plot the position function

r(t) = -ti + (t^3)/3)j

over the interval t  = -2 < t < 2

where i and j are unit vectors. I've drawn it out by hand but I can't get the same result through Matlab. My problem is that I'm not really sure about how to get those i and j vectors into the expression.

I tried something like

ri = [1;0;0]
rj = [0;1;0]
t = -2:0.1:2
r = -t.*ri + ((1/3)*t.^3).*rj

but got a message saying "Error using . * Matrix dimensions must agree."

Can someone give me some pointers on how to do this.

Many thanks.

Answer 1

[Walter Roberson]

hint:

fx = @(x) sin(x.^2) + cos(x) * 1j;
y = fx(0:.1:1);