Programming
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This comprehensive guide focuses on using MATLAB for numerical computing, specifically tailored for scientists and engineers. Learn to write basic programs utilizing if and for statements, convert for-loops into matrix operations, and employ relational and logical operators. Through engaging exercises, you will generate random matrices, implement conditional statements, and explore functions like Taylor series expansions. By the end of this program, you'll be adept at creating effective MATLAB scripts to solve various scientific and engineering problems.
Programming
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Programming Numerical Computing with . MATLAB for Scientists and Engineers
You will be able to • Write simple MATLAB programs using if statement, • Write simple MATLAB programs using for statement, • Convert a for-loop based program into a matrix operation version.
Relational Operators • Operators • Results are logicals < <= > >= == ~= a = 5 < 8 b = [1:2:8] > 3 c = [2:2:13] == [ 0:3:17 ] A = randint(3,4,10) A>5 A(A>5) = 5
Exercise 1: Hate 4 • Generate a 5x6 matrix A with random integers between 0 and 10. • If some elements of matrix A is 4, replace it with 0. • If some elements of matrix A is odd, subtract 1 from the elements. hate4.m
Logical Operators • Operators • Built-in Functions • Examples & | ~ and(A,B) or(A,B) not(A) xor(A,B) all(A) any(A) find(A) find(A>d)
Conditional Statement: if • if condition • if condition – else F n = input('Enter an integer: '); if mod(n,2) fprintf('%d is an odd integer.\n', n ); end x<0 T S1 S1 S2 n = input('Enter an integer: '); if mod(n,2) fprintf('%d is an odd integer.\n', n ); else fprintf('%d is an even integer.\n', n ); end F x<0 T S1 S1 S2
Exercise 2 Volume in a Water Tank • Find the volume of the water tank below when the depth is h. 10m 8m 8m 8m h m 6m 6m
Solution 2 • Function m-file • Commands water_volume.m
if – elseif – else – end • Nested If if A x = a else if B x = b else if C x = c else x = d end end end if A x = a elseif B x = b elseifC x = c else x = d end F F F if elseif elseif T T T S1 S2 S3 S4
For Loops for n=a:b statements end i=0; for t=0:0.1:100 i = i+1; x(i) = sin(2*pi*200*t); end for n=1:5 for m=5:-1:1 a(n,m)=n^2 + m^2; end end t=0:0.1:100; x = sin(2*pi*200*t); n=1:5; m=1:5; [nn,mm]=meshgrid(n,m); a=nn.^2 + mm.^2;
Example • Taylor series of sine function • Write a function y= Tsin(x,n), which is the partial sum of n-terms.
Exercise 3 • Taylor series of exp(x). • Write a function y= Texp(x,n), which is the partial sum of n-terms. Use Texp() to plot exp(x), Texp(x,5), Texp(x,10), Texp(x,100).
Solution 3 • Function m-file • Commands and Screenshot Texp.m
While Loops i=0;t=0; while t<=100 i = i+1; x(i) = sin(2*pi*200*t); t = t+0.1; end i=0; for t=0:0.1:100 i = i+1; x(i) = sin(2*pi*200*t); end t=0:0.1:100; x = sin(2*pi*200*t);
Lotto Numbers • disp('I generate Lotto numbers'); • disp('Good Luck!'); • B=[]; • for i=1:5 • L=0; • while L ~= 6, • fprintf('Try - %d \n ', i ); • A=floor(rand(1,6)*45)+1; • A=unique(A); • L=length(A); • end • B(i,:) = A; • pause(1); • end • B
Branch apple=100; if apple < 5 disp('few'); elseif apple < 20 disp('a few'); else disp('a lot'); end mon = 10; switch mon case 1 month = 'January'; case 2 month = 'February'; otherwise month = 'Others'; end
Branch x = 2.7; units = 'm'; switch units case {'inch', 'in'} y = x * 2.54; case {'feet', 'ft'} y = x * 2.54 * 12; case {'meter', 'm'} y = x * 100; case {'milimeter', 'mm'} y = x / 10; case {'centimeter', 'cm'} y = x; otherwise y = nan; end Unlike C, no break!
