# plot01.m - Simple Plot

## Contents

## Plotting y = x^2

To plot `y = x^2`, we follow these steps:

- First create an array of x values. We choose plot the function on interval [0,10] with data points spaced every 0.5.
- Next, square each element in the
`x`array and store it in a new array`y` - We use the plot command and label the axes

Here's the code:

x = 0:0.5:10; % x values range from 0 to 10 in steps of 0.5 y = x.^2; % square each element in x array and store in y plot(x,y) % plot y vs. x (defaults as blue line connecting points) xlabel('x') % label horizontal axis ylabel('y') % label vertical axis title('Graph of y = x^2') % title

And here's the plot:

## Plot Styles and Color Options

Matlab offers a simple method of creating plots with different line and marker styles and colors. Here's a list of the basic options:

**Color Options:**

'r' = red 'g' = green 'b' = blue 'y' = yellow 'c' = cyan 'm' = magenta 'k' = black 'w' = white

**Line Options:**

'-' = solid line ':' = dotted line '--' = dashed line '-.' = dash-dot line

**Marker Options:**

'o' = circle '+' = plus 's' = square '*' = star '^' = up triangle (carrot = shift-6) 'v' = down triangle (lowercase v) 'x' = x 'd' = diamond

## Example: Red Line

To make the blue line in the previous example red, replace the `plot` command in the previous example with the command:

```
plot(x,y,'r-')
```

the dash '-' says to connect the points together with a solid line and the 'r' says to color the line red. Here's the result:

## Example: Thick Red Line

To change the thickness of the line use the `'LineWidth'` option like this:

plot(x,y,'r-','LineWidth', 2)

## Example: Blue Circles

To plot blue circles at each point use the following command:

```
plot(x,y,'bo')
```

the 'o' symbol says to draw a circle at each data point. Here's the result:

## Example: Filled Blue Circles

To draw draw filled markers use the `'MarkerFaceColor'` option like this:

plot(x,y,'bo','MarkerFaceColor','b')

In principle, you can use a different color to fill in the marker than you use to draw the marker, but this is generally not desireable.

## Example: Big Magenta Squares

In this example we draw black squares with the 'ks' option and then fill them in with magenta using `'MarkerFaceColor'`. We use `'MarkerSize'` to adjust the saze and make them big.

plot(x,y,'ks','MarkerFaceColor','m','MarkerSize',12)

## Custom Colors

We can create custom colors by specifying their RGB (red, blue, green) values in a 1x3 matrix like this:

c = [R G B];

where R, G and B are values between 0 and 1. If all three values are 1, then white is produced. If all three are zero then it gives black. Here's a list of RGB values around a color wheel:

The following example uses dark green, filled circle markers:

plot(x,y,'o','Color',[0 1/2 0], 'MarkerFaceColor', [0 1/2 0])