command.
2.
Using the
hold on
,
hold off
commands.
-10
-8
-6
-4
-2
0
2
4
6
8
10
-3000
-2000
-1000
0
1000
2000
3000
3x
3
9x
2
18x

1. USING THE plot() COMMAND
Plots three graphs in the same plot:
y versus x,
y1 versus x1,
and y2 versus
x2.
By default, MATLAB makes the curves in different
colors.
Additional curves can be added.
The curves can have a specific style by adding
specifiers after each pair, for example:
>> plot(x,y,x1,y1,x2,y2)
>>plot(x,y,’-b’,x1,y1,’—r’,x2,y2,’g:’)

EXAMPLE
Plot the function 3x
3
and its first and second derivate for a
range of x from -10 to 10.
>> x=-10:1:10;
% Range of x values
>>y=3*x.^3;
% Calculating the function 3x
3
>>dy=9*x.^2;
% Calculating the first derivate 9x
2
for each x
value
>>dy2=18*x;
% Calculating the second derivate
>> plot (x,y,’r-’,x,y,’b:’,x,dy2,’g--’)

hold on
Holds the current plot and all axis properties
so that subsequent plot commands add to
the existing plot.
hold off
Returns to the default mode whereby plot
commands erase the previous plots and
reset all axis properties before drawing new
plots.
2. hold on and hold off
COMMANDS
TO PLOT MULTIPLE GRAPHS IN
THE SAME PLOT
NOTE: This method is useful when all the information (vectors)
used for the plotting is not available at the same time.

EXAMPLE
Plot the function 3x3 and its first and second derivate for a range of x from -10 to 10.
>> x=-10:1:10;
% Range of x values
>>y=3*x.^3;
% Calculating the function 3x3
>> plot (x,y,’r-’)
>>hold on
>>dy=9*x.^2;
% Calculating the first derivate
>> plot (x,y,’b:’)
>>dy2=18*x;
% Calculating the second derivate
>>plot (x,dy2,’g--’)
>>hold off

FORMATTING PLOTS
A plot can be formatted to have a required appearance.
With formatting you can:
Add title to the plot.
Add labels to axes.
Add legend.
Change range of the axes.

FORMATTING COMMANDS
1] title(‘string’)
Adds the string as a title at the top of the plot.
>>x=-10:1:10;
>>y=3*x.^3;
>> plot (x,y);
>> title (‘Title of the Plot’)
2] xlabel(‘string’)
Adds the string as a label to the
x
-axis.
>> xlabel (‘x range’)

FORMATTING COMMANDS
3] ylabel(‘string’)
Adds the string as a label to
the
y
-axis.
>> ylabel (‘ y values’)
4] axis([xmin xmax ymin
ymax])
Sets the minimum an
maximum limits of the
x
- and
y-axes.

FORMATTING COMMANDS
5] legend(‘string1’,’string2’,’string 3’…)
For each line plotted,
the legend shows a sample of the line type, marker
symbol, and color beside the text label you specify.
>> hold on
>> dy=9*x.^2
>> plot (x,dy,’g--’)
>>dy2=18*x;
>>plot(x,dy2,’r:’)
>>legend(‘y’, ’First derivative’, ’Second derivative’)

FORMATTING A PLOT IN THE
FIGURE WINDOW
Figures
can be formatted interactively from the figure window
Use the edit
menu to edit
1] Axes
properties
2] Figure
properties
3] Current
object
properties
Use the insert
menu to
interactively
insert the
1]x label
2]y label
3] legend
4] textbox
5] colorbar

PLOTTING MULTIPLE
FIGURES IN ONE PAGE
subplot(m,n,p)
divides the figure page into
an m-by-n grid. Combined with the plot
command it creates a plot in the grid
position specified by p.

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