《MATLAB及其工程应用》第8讲.ppt

MATLAB Its Applications In Engineering 李清都 副教授 liqd@cqupt.edu.cn Lect. 8: MATLAB Modeling The ability to solve a problem Divide the big task into several small sub-tasks Think more … Try to make things easier Think about how the plane looks like when it was created in 1900s. And now? An example Use MATLAB to model an physics experiment Thomas Yang’s double-slit experiment Young’s double-slit experiment S：the single slit S1,S2: the double-slit pair d：the distance between the two slits L：the distance between the slits and the screen Questions Why there are strips? Because the colors on screen are differnt； Why the colors are differnet? Because the mixing results of the lights from the two slits are different. Why the mixing results different？ Because the phase of the lights are different。 Why phase different？ Because the distances they pass are different。 Why the distances different？ Well, well, because they are from TWO slits, not one. The formula How to Model? Calculate the luminance of one point on the screen Calculate the luminance of more points on the screen Turn the values of different luminance into a picture Modify ‘d’, ‘L’ to see what will happen? How to generate a picture The concepts of a pixel? Pictures are build up by pixels. Color map OK, let’s program The result ! Further Consideration How to model if the light at ‘s’ is not a pure light? Can you generate a colored picture according to the wavelength you defined? Assignment: Excises 5.18 (please refer to Example 4.7 and formula 4.5, 4.6) 6.1 (only for intensive training class) * * * Contents Covered: How to model an engineering problem with MATLAB? Objectives: Grasp the skill of using MATLAB to model and solve a problem Grasp the skill of writing and debugging MATLAB problems … clf; figure(gcf); NClevels = 255; Br = (B/max(B))*NClevels; …