# Create Math Graph using Matlab?

1. Aug 27, 2015

### basty

How do I create a graph of y = x^2 + x + 1 in Matlab?

Where I could create the above math graph in Matlab (please see below image)?

2. Aug 27, 2015

### soarce

Type in command window the following:

Code (Text):

x=[-5:0.2:5];
y=x.*x+2*x+1;
plot(x,y);

3. Aug 27, 2015

### basty

What is the meaning of below code?

x=[-5:0.2:5];

Also, is y=x.*x+2*x+1; mean $y = x^2 + 2x + 1$?

If so, then there is a mistake with the above code.

It should be $y = x^2 + x + 1$.

What is the correct code of $y = x^2 + x + 1$ in Matlab?

4. Aug 27, 2015

### soarce

You can remove the factor of 2, I put it by mistake.

Anyway, you would better start a free tour of Matlab documentation.

5. Aug 28, 2015

### basty

Thank you, but, the documentation doesn't help.

Can someone please tell me the order of creating math graph in Matlab with explanation?

6. Aug 28, 2015

### Staff: Mentor

7. Aug 28, 2015

### RUber

I agree that taking the MATLAB tutorials would be helpful for you. These are basic syntax questions.

This command tells matlab to create a vector called "x" with initial value -5 and final value 5 with intermediate values spaced .02 units apart.
You can adjust your initial and final values as well as your step size as you see fit.
y = x . ^2 + x + 1;
will create a vector called "y" which is the same size as x and for every value in x, it will compute x^2 + x +1. Notice the dot before the exponent: .^2 means to return the square of each element...as opposed to ^2 which tries to square the vector using matrix multiplication.

plot(x,y) is the simplest graphing option and requires that the two vectors be the same length.