general computer science for engineers cisc 106 lecture 05

General Computer General Computer Science Science

for Engineersfor EngineersCISC 106CISC 106

Lecture 05Lecture 05

James AtlasComputer and Information Sciences

6/22/2009

Lecture OverviewLecture OverviewReviewPlotting

Simple PlotsArraysRecursion

ReviewFor loopIf statement

Branching ConstructsWe already covered the IF

statement

Why would IF be considered a “branch”?

Branching ConstructsWhy would IF be considered a

“branch”? ◦Let’s look at what happens to our

code when it is executing on the CPU

Switch constructswitch (switch_expression)case case_expr_1 statement 1 statement 2case case_expr_2 statement 1 statement 2otherwise statement 1 statement 2end

Switch constructcolor = ‘yellow’;switch (color)case ‘red’ disp(‘Stop now!’);case ‘green’ disp(‘Proceed through intersection.’);case ‘yellow’ disp(‘Prepare to stop.’);otherwise disp(‘Illegal color encountered.’);end

For loop for sum integers total = 0;

for i = 1:1:100 loop starts at 1 total = total+i; loop increments

by 1 end

While loop

while expression statementend

While loop for sum integers total = 0; i = 1;

while i <= 100 loop starts at 1 total = total+i; loop increments

by 1 i = i + 1;

end

Recursion

PlotPlotUsing the plot command

plot(<array 1>,<array 2>)

where array1 is the x-axis and array2 is the y-axis

NOTE: array1 and array2 must be equal in terms of size of dimensions!

PlotPlotFor example:

x=[1 2 3 4 5];y=[10 20 30 40 50];

plot(x,y)

PlotPlotOther useful command with plotxlabel(‘<string>’) – sets the label for

the x-axisylabel(‘<string>’) – sets the label for

the y-axisgrid on – creates a grid title(‘<string>’) – sets title of the plot

PlotPlotFor example:

x=0:1:10;y=x.^2 - 10.*x + 15;

plot(x,y)

Plot commandstitle(‘Graph Title’);xlabel(‘X axis label’);ylabel(‘Y axis label’);grid on;legend(‘series 1’, ‘series 2’, ..., ‘BR’);

print -dpng mygraph.png