More stuff on plotting

1. More stuff on plotting

2. Define x and y and call the plot function

3. Engineers always add … • Title title(‘y = cos(x)’) • X axis label, complete with units xlabel(‘x-axis’) • Y axis label, complete with units ylabel(‘y-axix’) • Often it is useful to add a grid grid on Single quotes are used.

4. Change the line type in a plot • Example plot(x, y, ':ok') • strings are identified with single quotes • the : means use a dotted line • the o means use a circle to mark each point • the letter k indicates that the graph should be drawn in black • (b indicates blue)

5. Available choices

6. specify the drawing parameters for each line after the ordered pairs that define the line

7. Subplots • The subplot command allows you to subdivide the graphing window into a grid of m rows and n columns • subplot(m,n,p) rows columns location

8. subplot(2,2,1) 2 columns 2 1 2 rows 3 4

9. 2 rows and 1 column

10. Other Types of 2-D Plots • Polar Plots • Logarithmic Plots • Bar Graphs • Pie Charts • Histograms • X-Y graphs with 2 y axes • Function Plots

11. Three Dimensional Plotting • 3D Line plots (i.e. plot3(x,y,z)) • Surface plots (i.e. mesh(z) and surf(z)) • Contour plots

12. Mesh plots • mesh(z) plots out a 3D plot • The z-axis are the values of ‘z’ • The x-axis is each point corresponding to a column • The y-axis is each point corresponding to a row Example: Z = [1 2 3; 4 5 6]mesh(Z)

13. Mesh plots continued… • Can also do mesh(x,y,z)  this allows the x and y axis to be something else other than the number of rows and columns • x and y need to have the same dimensions as z. • If x and y are vectors, need to use meshgrid to make them a 2D matrix.

14. meshgrid example Example: Z = [1 2 3; 4 5 6] %2x3 matrixx=[0:3:6] %number of columns is 3 y=[0:6:6] %number of rows is 2 [X,Y] = meshgrid(x,y) %new X and Y that are 2x3 matrices mesh(X,Y,Z) xlabel(‘X’) ylabel(‘Y’) zlabel(‘Z’)

15. meshgrid example output Z = 1 2 3 4 5 6 x = 0 3 6 y = 0 6 X = 0 3 6 0 3 6 Y = 0 0 0 6 6 6

16. surf plots • A surf plot is basically the same as mesh plot except that surf plots give a color surface instead of a mesh Ex: surf(X,Y,Z)

17. In-class assignment • Problems 4.6, 4.7, and 4.9 from the Matlab book