I want to plot an equation using a for-loop. I have tried several different ways, but keep getting the apparently common error "Subscript indices must either be real positive integers or logicals". The equation I want to plot is *y(x) = (x^4)-(4\*x^3)-(6\*x^2)+15*.

The last code I tried was the following:

```
y(0) = 15;
for x = [-3 -2 -1 0 1 2 3 4 5 6];
    y(x) = (x^4)-(4*x^3)-(6*x^2)+15;
end
plot(x,y)

```