EGR106 Week 6

1. EGR106 Week 6 • MATLAB FILES • Two Dimensional Plots • Multiple Plots • Plot Formatting • Homework

2. MATLAB Files • Script files (m files) • Text files • Contain MATLAB commands • Data Files (mat files) • binary files • Contain arrays (data) • Use “save” and “load” commands to write and read

3. Two Dimensional Plots • Line type • plot(x,y,’--’) gives a dashed line • Line color • plot(x,y,’g’) gives a green line • Line thickness • Markers • plot(x,y,’--r*’,’linewidth’,2,’markersize’,12) • Dashed red line with * marker

4. Multiple Plots • Plot(x, y1, x, y2) Plots y1 and y2 vs x • hold on • Keeps the plot window open for additional lines on the same plot • hold off • Stops writing to the plot • subplot(n,m,k) • Selects plot k in an nxm array of plots. • Used for multiple plots on the same page.

5. Plot Formatting • xlabel, ylabel • xlabel(‘time (sec)’) • title • title(‘Problem 3 Solution’) • text • text(x,y,’your message at coordinates x,y’) • legend • legend(‘first curve’,’second curve’) • used for multiple curves on a single plot

6. Plot Formatting • Subscripts and superscripts • Greek letters • Rotating text

7. Line Properties and Values plot(x,y, 'linewidth',5 ) line width is 5 “points”

8. >> x=0:2:10; >> y=x.^2; >> plot(x,y,'--r*','linewidth',2,'markersize',12) >> text(2,50,'\fontsize{30} \alpha Profit= x^2 ', 'rotation',45)

9. Line Specifiers plot(x,y, ' r : d ' ) red dotted line diamonds

10. Multiple Plots on the Same Axes • Plot allows multiple sets of arrays and line specifiers: Note colors rotate

11. Two Useful Commands • figure • alone it opens a new window • figure(n) takes you to window n • ginput(1) • creates crosshairs on the screen • returns (x,y) location of cursor at mouse click • ginput(n) returns n pairs of locations

12. Formatting Plots – Adding Text • Week 1: • xlabel( 'string' ) • ylabel( 'string' ) • title( 'string' ) • text( x, y, 'string' ) • New: • gtext( 'string' ) – cursor controlled • legend( 'string1', … 'stringn', loc)

13. Multiple Axes in One Figure - Subplot subplot(2,2,1) plot(x1,y1) subplot(2,2,2) etc. Argument is rows, columns, choice

14. Other Types of 2-D Plots - Polar x = 1:100; r = log10(x); t = x/10; polar( t, r ) magnitude angle in radians

15. Other Notes • Line specifiers, properties, axis, grid, … work on many of the plot types • Most of these tools have additional features – use the help function • 3-dimensional plots are available (chapter 9) with viewpoint options