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ENGR 0012 – Spring 2007
Thursday, January 4
th
Dr. Lund
Course Website:
www.engr.pitt.edu/~eng
My Website:
www.engr.pitt.edu/freshman/academic/
engr0715/engr0012.html
Programming (In a nutshell)
• Take input
(e.g. variable values, data, signals…)
• Process input
(Tools include math functions, decision structures, while loops, for loops…)
• Generate output
(e.g. variable values, plots, control signals …)
Good Practices
- Know your programming language
- Comment, comment, comment
- Define problem and desired output
- Break problem down into primary components
- Write code in components and debug as you go
MATLAB Review Topics for Today
- While Loops
- Decision Structures
- IF – ELSEIF – ELSE
- SWITCH – CASE – OTHERWISE
- Loop Counters
- Array Indexing
- Plotting
While Loops
disp('Start of problem') a = 4 while a > 1 b = 2; while b <= a b = b + 1; disp(ab) end a = a - 1 end disp('End of problem')*
Nested while loop
Loop counters
(Notice how all loop counters must be initialized before the loop)
If - Elseif – Else Branching
a = [5 8 -4 -3 7 1 9]; N=0; while (N <= 5) N=N+ if ( N==1 | N > 6) Output = a(N) ; disp(Output) elseif ( (N == 3) | (N >= 5) ) Output = a(N+1); disp(Output) else Output = a(5); disp(Output) end end
Loop counter
Array Indexing
Switch – Case
Branching
v=[1 2 3 4 5 6 7]; k=5; while k > 0 switch (k+1) case {1,5} new=v(k)+v(k+1) case {4,6} new=v(k) case 2 new=- otherwise new=v(k+2) end k = k - 1; end
Array indexing
Loop counter
Array Indexing
array = [1 2 3 4 5 6 7]
Array indexing can be used to isolate specific
values from an array. Elements of an array
can be used or manipulated independently of
one another.
Subplots
(^00 2 4 6 )
2
4
6
8 Linear Plot
x
y
0 2 4 6 8
10 0.
10 0.
Semi-Log Plot
LN(y)
x 10
0
10 0.
10 0.
Log-Log Plot
LN(y)
LN(x)
- Creates plots in tiled positions.
- SUBPLOT(m, n, p), breaks the Figure window into an m-by-n matrix of small plots, selects the p-th axes for for the current plot.
- The axes are counted along the top row of the Figure window, then the second row, etc.
- For example,
SUBPLOT(2,1,1), PLOT(x,y) SUBPLOT(2,1,2), PLOT(x,z)
plots x vs. y on the top half of the window and x vs. z on the bottom half.
Subplot command
Subplot
- Type help subplot in command window
- Click on doc subplot link at bottom of help
output
