plot using matlab

1. 2)fplot function
• The MATLAB function fplot can be used
to plot a function of one variable in a
specified range.
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2. See also
•Function plot
>>fplot(‘function’,[xmin xmax],’property’)
Example :
>>fplot(‘sin’,[0 2*pi],’r:’)
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3. fplot function
• » fplot('sin(x)',[-pi pi])
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4. fplot function
• » fplot('sin(x)',[-pi pi])
-2 0 2
-1
-0.5
0
0.5
1
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5. fplot function
• » fplot('exp(-x)*sin(x)',[0 2])
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6. fplot function
• » fplot('exp(-x)*sin(x)',[0 2])
0 0.5 1 1.5 2
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
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7. Adding a grid
• You can use the command:
• grid on
• to add grid lines to your plot. This
increases the readability of the graph.
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8. Adding a grid
• You can use the command:
• grid on
• to add grid lines to your plot. This
increases the readability of the graph.
• To remove these grid lines, use:
• grid off
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9. Adding a grid
• » fplot('exp(x)-x-2',[-3 3])
• » grid on
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10. Adding a grid
• » fplot('exp(x)-x-2',[-3 3])
• » grid on
-3 -2 -1 0 1 2 3
-5
0
5
10
15
20
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11. 3D Plotting
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12. plot3 function
• The MATLAB function plot3 is used to
plot space curves.
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13. plot3 function
• The MATLAB function plot3 is used to
plot space curves.
• Space curves are usually represented by
parametric equations:
• x = x(t), y = y(t), z = z(t)
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14. plot3 function
• The MATLAB function plot3 is used to
plot space curves.
• Space curves are usually represented by
parametric equations:
• x = x(t), y = y(t), z = z(t)
• Steps followed and options available for
plot3 is similar to that of plot.
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15. plot3 Example 1
• Example: Plot the line
• x = t + 2, y = t - 2, z = t, 0 < t < 1
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16. plot3 Example 1
• Example: Plot the line
• x = t + 2, y = t - 2, z = t, 0 < t < 1
>> t=0:0.01:1;
>> x=t+2;
>> y=t-2;
>> z=t;
>> plot3 (x,y,z,'r.')
>> grid on
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17. plot3 Example
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18. plot3 Example 2
• Example: Plot the circle
• x = 1, y = 5 cos t, z = 5 sin t, - < t < 
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19. plot3 Example 2
• Example: Plot the circle
• x = 1, y = 5 cos t, z = 5 sin t, - < t < 
» t=-pi:0.01:pi;
» x=ones(length(t),1);
» y=5*cos(t);
» z=5*sin(t);
» plot3(x,y,z,'r.')
» grid on
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20. plot3 Example
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21. plot3 Example 3
• Example: Plot the helix
• x = cos t, y = sin t, z = t, 0 < t < 10 
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22. plot3 Example 3
• Example: Plot the helix
• x = cos t, y = sin t, z = t, 0 < t < 10 
t=0:0.01:10*pi;
x=cos(t);
y=sin(t);
z=t;
plot3(x,y,z,'r.')
grid on
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23. plot3 Example
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24. plot3 function
• The MATLAB function plot3 can be used
also to plot multiple 2D curves in 3D.
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25. plot3 Example 4
• Example: Plot together
• sin x, cos x
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26. plot3 Example 4
• Example: Plot together
• sin x, cos x
x=0:0.01:3*pi;
y1=zeros(size(x));
y2=ones(size(x));
z1=sin(x);
z2=cos(x);
plot3(x,y1,z1,'.r',x,y2,z2,'.g')
grid on
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27. plot3 Example 4
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28. mesh function
• The MATLAB function mesh is used to
plot surfaces.
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29. mesh function
• The MATLAB function mesh is used to
plot surfaces.
• Surfaces are usually represented by a
function of two variables:
• z = f(x, y)
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30. mesh function
• The MATLAB function mesh is used to
plot surfaces.
• Surfaces are usually represented by a
function of two variables:
• z = f(x, y)
• To use this function we have to use
meshgrid first to generate to pairs (x, y)
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31. meshgrid by example
>> x=0:2
x = 0 1 2
>> y=0:2
y = 0 1 2
>> [X,Y]=meshgrid(x,y)
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32. meshgrid by example
>> x=0:2
x = 0 1 2
>> y=0:2
y = 0 1 2
>> [X,Y]=meshgrid(x,y)
X = 0 1 2
0 1 2
0 1 2
Y = 0 0 0
1 1 1
2 2 2
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33. mesh Example 1
• Example: Plot the surface
• z = x2 + y2
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34. mesh Example 1
• Example: Plot the surface
• z = x2 + y2
x=-3:0.01:3;
y=-3:0.01:3;
[X,Y]=meshgrid(x,y);
z=X.^2+Y.^2;
mesh(X,Y,z)
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35. mesh Example 1
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36. mesh Example 2
• Example: Plot the surface
• 7 x - y + z=3
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37. mesh Example 2
• Example: Plot the surface
• 7 x - y + z=3
>> x=-3:0.1:3;
>> y=-3:0.1:3;
>> [X,Y]=meshgrid(x,y);
>> z=3-7*X+Y;
>> mesh(X,Y,z)
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38. mesh Example 2
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39. Other Useful Graphics Commands
You may find the following set of commands useful:
Function Used to
plot3 Create a graph for a 3D data representing a space curve
loglog Create a graph with logarithmic scales for both axes
semilogx Create a graph with logarithmic scale for the x axis only
semilogy Create a graph with logarithmic scale for the y axis only
plotyy Create a graph with y-tick labels on the left and right side
gtext Position text using the mouse
clf Clears the figure
ginput Gather data by clicking on points in the plot
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