MATLAB 2-D Plotting. Matlab has many useful plotting options available! We ll review some of them today.

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1 Class15

2 MATLAB 2-D Plotting Matlab has many useful plotting options available! We ll review some of them today. help graph2d will display a list of relevant plotting functions.

3 Plot Command Plot command used to make basic 2D plots. Simplest form is plot(x,y) x and y are vectors that have same size (number of elements) but any dimension x-values on horizontal axis, y-values on vertical axis

4 One way to plot a function of an independent variable: 1. Create a vector of values of the independent variable 2. Create a vector of value of function at every element of above vector 3. Plot using plot(x,y)

5 Example Problem: plot y = x cos(6x) colon and dot notation for arrays x = [ 2:0.1:4]; y = 3.5.^( 0.5*x).*cos(6*x); plot(x,y) xlabel('value of x') ylabel('value of y') title('problem 10') text(0,1, engr 104 week X') standard form for plot, xv on the horiz axis, y on vert axis. annotation tools

6 Figure Window with Plot of function y = x cos(6x)

7 To copy entire Figure Window into another program, e.g., Word, PowerPoint 1. Click on Figure Window to make it current window 2. Use Snipping Tools in Windows

8 To copy just plot area of Figure Window into another program, e.g., Word, PowerPoint 1. In Figure Window, select Edit Copy Figure 2. Paste into other application

9 Spruce up a plot by adding Axis labels (<- important!) Title Legend Text Grid Custom axis ranges

10 Common MATLAB plotting commands Command xlabel ( text ) ylabel ( text ) title ( text ) text (x, y, text ) axis ([xmin xmax ymin ymax]) grid Description Adds a text label to the horizontal axis Adds a text label to the vertical axis Puts text in a title at the top of the plot Place text at specified coordinates Sets the minimum and maximum limits of the x- and y- axes Puts grid lines on the plot

11 Plot Formatting Commands Command line manipulation is available through optional additional arguments: plot(x,y, 'linespecifiers' ) line specifiers are optional and can be used to define the style and color of the line and the type of markers (if markers are desired). Line Style Specifier solid (default) - dashed - - dotted : dash-dot -. Line Color Specifier red r green g blue b cyan c magenta m yellow black white y k w

12 Marker Type Specifiers Marker Type Specifier plus sign + circle asterisk * point. cross triangle (pointed up) triangle (pointed down) o x ^ v Marker Type square diamond five-pointed star six-pointed star Specifier s d p h triangle (pointed left) < triangle (pointed right) >

13 Notes about specifiers The specifiers are typed inside the plot command as strings. Within the string the specifiers can be typed in any order. The specifiers are optional. This means that none, one, two, or all three can be included in the command.

14 A plot can be made from measured data or from an equation General form: plot(x,y, ' ') The order of specifiers is not important! Color: k black r red b blue g green y yellow c cyan w white m magenta Symbol:. point o circle x x-mark s square d diamond etc. Line type: - solid : dotted -- dashed -. dash-dot

15 Example plot command w/ Line Specifiers plot(x,y, ' r : d ' ) red dotted line diamonds A red dotted line connects the points that are marked with diamond markers.

16 Plot Formatting Commands More command line manipulation: optional additional arguments: plot(x,y, 'line specifiers, Property name, Property value) Property name and property value can be used to specify the line width, and marker s size and edge, and fill colors. Property name Description Possible property values linewidth Specifies the width of the line. A number in units of points (default 0.5) markersize markeredgecolor markerfacecolor Specifies the size of the marker Specifies the color of the marker, or the color of the edge line for filled markers Specifies the color of the filling for filled markers A number in units of points Color specifiers from the earlier table, typed as string Color specifiers from the earlier table, typed as string.

17 Example plot command w/ Properties plot(x,y, 'linewidth',7 ) line width is 7 points

18 solid black line with circle markers Line width, 3 units (default 0.5) plot(x,y, '- k o', 'LineWidth', 3, 'MarkerSize', 6, 'MarkerEdgeColor','red','MarkerFaceColor','green')

19 Multiple Plots on the Same Axes Plot allows multiple sets of arrays and line specifiers: Note colors differ

20 Can use line specifiers for multiple plots.

21 Can also use hold to freeze the plot Following the hold on command, the first plot remains open, including axis properties and formatting. Additional graphs are added with each plot command, until the command hold off is typed. Now, note colors

22 Other Plot Formatting Commands Adding Text xlabel( 'string' ) ylabel( 'string' ) title( 'string' ) text( x, y, 'string' ) gtext( 'string' ) cursor controlled legend( 'string1', 'stringn', pos) Location where text is started text location is controlled by cursor Formatting of the text can be done either by adding modifiers inside the string, or by adding the command optional PropertyName and PropertyValue arguments following the string.

23 Legend Position pos = -1 pos = 0 pos = 1 pos = 2 pos = 3 pos = 4 Places the legend outside the axes boundaries on the right side. Places the legend inside the axes boundaries in a location that interferes least with the graphs. Places the legend at the upper-right corner of the plot (default) Places the legend at the upper-left corner of the plot Places the legend at the lower-left corner of the plot Places the legend at the lower-right corner of the plot

24 Example plot with specifiers and legend

25 Some text modifiers Modifier \bf \it \rm \fontname{fontname} \fontsize{fontsize} Effect bold font italic style normal font specified font is used specified font size These modifiers affect the text from the point that they are inserted until the end of the string. It is also possible to have the modifiers applied to only a section of the string by typing the modifier and the text to be affected inside braces { }.

26 Using PropertyName and PropertyValue to format text. Property Name Description Possible Property Values Rotation FontAngle FontName FontSize FontWeight Specifies the orientation of the text Specifies italic or normal style characters Specifies the font for the text Specifies the size of the font Specifies the weight of the characters Scalar (degrees) Default: 0 normal, italic Default: normal Font name that is available in the system Scalar (points) Default: 10 light, normal, bold Default: normal

27 Using PropertyName and PropertyValue to format text. Property Name Description Possible Property Values Color Specifies the color of the text Color specifiers as presented earlier BackgroundColor EdgeColor Specifies the background color (rectangular area) Specifies the color of the edge of a rectangular box around the text Color specifiers as presented earlier Color specifiers as presented earlier LineWidth Specifies the width of the edge of a rectangular box around the text Color specifiers as presented earlier General Form: text(x,y, text as string,propertyname,propertyvalue)

28 Example: gtext( 'cosine', 'fontsize', 20, 'rotation', 45, 'color', 'red', )

29 Greek Characters Character in the string \alpha \beta \gamma \theta \pi \Phi \Delta \Gamma \Lambda \Omega \Sigma Greek letter a b g D G L S Greek characters can be included in the text by typing \name of the letter within the string.

30 Example superscript command Add greek letters, sub and superscripts E.g. gtext( '\beta_1 x^2' ) subscript command

31 Formatting Plots The Axes Adding a grid grid Setting the axis limits: axis( [ xmin xmax ymin ymax ] )

32 E.g.

33 Can plot on logarithmic axes using: semilogy(x,y) plots y versus x with log (base 10) scale for the y axis and linear scale for the x axis. semilogx(x,y) plots y versus x with log (base 10) scale for the x axis and linear scale for the y axis. loglog(x,y) plots y versus x with log (base 10) scale for both axes. Note negative data is ignored

34 Script File for Formatted 2D plot % Example plot for demonstrating 2D plots in MATLAB x=[10:0.1:22]; y=95000./x.^2; xd=[10:2:22]; yd=[ ]; plot(x,y,'-','linewidth', 1.0) xlabel('distance (cm)') ylabel('intensity (lux)') title ('\fontname{arial}light Intensity as a Function of Distance', 'Fontsize',14) axis([ ]) text(14, 700, 'Comparison between theory and experiment.', 'EdgeColor', 'r', 'LineWidth', 2) hold on plot(xd, yd, 'ro--', 'linewidth', 1.0, 'markersize', 10) legend('theory', 'Experiment', 0) hold off formatting text inside the title command formatting text inside the text command using PropertyName

35 INTENSITY (lux) Plot Title Legend Light Instensity as a Function of Distance Theory Experiment Y Axis Label 800 Comparison between theory and experiment Marker Text Label DISTANCE (cm) X Axis Label

36 Property Editor A plot can also be formatted interactively in the Figure Window by clicking on the plot and/or using the menus.. is limited to a single figure is tedious to repeat for other plots

37 MATLAB has interactive tools for modifying plots engr 104

38 Click on the arrow to start interaction Double click on some part of the figure to initiate choices

39 Modify text: Or the lines themselves:

40 Figure Files Save to create a.fig file

41 Figures outside MATLAB Print them: Copy for pasting

42 Multiple plots on same page - Subplot General Form subplot (m, n, p) Command divides the Figure Window into m x n rectangular subplots (3,2,1) (3,2,2) the value of p determines the current plot (3,2,3) (3,2,4) (3,2,5) (3,2,6)