Need help plotting simple graph in matlab

[Fairy111]

Homework Statement

I need to plot a graph in matlab,
i typed in the following,
V=[0:.2:20];
I=(V^3)-(1.4*V)+0.9;
plot(V,I)

It comes up with the error,
error using mpower, matrix must be square.

Any help into how to fix this problem would be great.

Thankyou

Homework Equations

The Attempt at a Solution

 

[Päällikkö]

A^2 = A*A, i.e. a matrix multiplication. Use A.^2 for element-wise operations:

V=[0:.2:20];
I=(V.^3)-(1.4*V)+0.9;
plot(V,I)

Ought to work.

 

[Mene]

It seems like you are trying to raise a vector to a power in your code, which is why you are getting the error message. The "mpower" function in Matlab is used for matrix exponentiation, not for raising a vector to a power. To plot a graph in Matlab, you need to have two vectors of the same length - one for the x-axis values and one for the y-axis values. In your code, you have defined the vector V for the x-axis values, but you need to define a vector for the y-axis values as well. You can do this by using the element-wise power operator (".^") instead of the matrix power operator ("^") in your code. So your code should be:

V = [0:.2:20];
I = (V.^3) - (1.4*V) + 0.9;
plot(V,I)

This should plot the graph for you without any errors. I hope this helps. If you have any further questions, feel free to ask.