7.2: Flowcharts
- Page ID
- 84477
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)By Carey A. Smith
A flowchart is a graphical representation of code logic. It is especially helpful to understand the logic of code with for loops and if-else logic.
An example is given here. More information can be found at:
https://en.wikipedia.org/wiki/Flowchart [en.Wikipedia.org]
Try to code this up
Solution
The corresponding code is:
for n = 1:12
if(mod(n,2) == 0)
disp([num2str(n),' is even'])
else
disp([num2str(n),' is odd'])
end
end
.
flowchart for primes
This flowchart and code show an algorithm to determine which numbers between 1 and 48 are prime numbers.
We already know that 2, 3, and 5 are prime, so the for loop starts at k = 6.
For each value it tests, it displays a message stating whether or not it is a prime number. It stores the prime numbers it finds in a vector called prime_list.
Try coding this logic.
Note that the for-loop automatically does the "k = k+1" shown at the bottom of the flowchart; do not code that line.
(There are more sophisticated and efficient prime-number algorithms; this one is an illustration of moderately complex logic.)
Solution
%% "for loop" example with “if-then-elseif” logic:
% Find the prime numbers between 1 to 48:
prime_list = [2,3,5] % Initial set of primes
for k = 6:48
if( mod(k,2) == 0) % Tests if k is divisible by 2
disp([num2str(k),' is not prime. It is divisible by 2'])
elseif (mod(k,3) == 0) % Tests if k is divisible by 3
disp([num2str(k),' is not prime. It is divisible by 3'])
elseif( mod(k,5) == 0) % Tests if k is divisible by 5
disp([num2str(k),' is not prime. It is divisible by 5'])
else
disp([num2str(k),' is prime.'])
% Add k to the list of primes:
prime_list = [prime_list, k];
end % end if
end % for k = 6:48
% Display the primes found
prime_list
This code is the attached file for_loop_primes.m
.
Homework:
1. Watch the following video from Robert Talbert
Then code the second example in the video about the temperature and rain. The corresponding flowchart is this:
Figure \(\PageIndex{i}\): Flowchart for Temperature, Rain, Wearing a Coat.
Put parentheses around the conditional expressions, even though the video did not do this. Examples:
if (temp < 50)
elseif (raining == 1)
.