Introduction To Matlab Class 2 Instructors: Hristiyan (Chris) Kourtev and Xiaotao Su, PhD Double click the matlab icon When prompted click “Skip”

Character Vectors And Numeric Vectors 'hello world' is referred to as a character string or a character vector [35, 26.3, 11, 4] is a numeric vector These are the two main data types in matlab h e l o w r d (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) 35 26.3 11 4 (1) (2) (3) (4)

Character Vectors (aka Strings) And Numeric Vectors How to convert between these two data types? What if I have a string, '39.5' and I want to add to it? num2str & str2num str2num('39.5') + 5 ['hello w', 'orld'] a = [3, 9]; b = [12.6, 8]; [a, b] c = ['1', num2str(39.5)] str2num(c) + 200

Formatting strings with sprintf result = sprintf(format_string, input1, input2 …) Format string: [flags][width][.precision][length] specifier Common Specifiers: %c character %s string %d integer %e or %E scientific notation %f floating point m = 44.5; k = ‘hello world’ res = sprintf(‘%s, it is %d degrees outside’, k, m); res will be “hello world, it is 44.5 degrees outside”

Formatting strings with sprintf Flags: - left justify; default is right 0 left pads the number with zeroes if padding specified Width: just a number Precision: just a number Examples sprintf('%01.2f', 12.4); %outputs 12.40 sprintf('%010.2f', 12.4); %outputs 0000012.40 sprintf('%.3e', 362525200); %outputs 3.625e+8 For further reference go to: http://php.net/manual/en/function.sprintf.php http://www.cplusplus.com/reference/clibrary/cstdio/sprintf/

Taking inputs Create a new program called math.m % math.m % % Carries out a series of calculations on two % numbers % written by Your Name July 2010

clear all; %take inputs num1=input('what is the first number?'); num2=input('what is the second number?'); %show calculations disp([num2str(num1), '+', num2str(num2), '=', num2str(num1+num2)]); disp([num2str(num1), '-', num2str(num2), '=', num2str(num1-num2)]);

boolean expressions == > >= < <= & | equals greater than Boolean expressions either return 1 for true or 0 for false Possible operators: == > >= < <= & | equals greater than greater than or equal to less than and or

Note: Put operations inside parenthesis so they are preformed first. 1==1 (1 + 1)==2 (5 + 5) < 10 (5 + 5) <=10 (1 == 1) & (2==3) (1 == 1) | (2==3) 5 + (5 < 10) Note: Put operations inside parenthesis so they are preformed first.

Conditionals (if statements) if(Boolean Expression) do something end you can also do this: if(boolean expression) else do something else or this: if(boolean expression) do something elseif(boolean expr2) do something else end

Back to math.m if ( (round(num1)==num1) & (round(num2)==num2) ) disp('num1 and num2 are integers') end

if ( (round(num1)==num1) & (round(num2)==num2) ) disp('num1 and num2 are integers') elseif(round(num1)==num1) disp('only num1 is an integer') elseif(round(num2)==num2) disp('only num2 is an integer') else disp('neither number is an integer') end

Task 1 == > >= < <= & | equals greater than Have math.m tell me which number is larger then the other “the biggest number is …” == > >= < <= & | equals greater than greater than or equal to less than and or

Tic and toc tic starts a timer toc tells you the number of seconds since when you ran toc

While loop while is a type of loop that runs while a condition is true while(boolean statement) %do something many times end %you would stop repeating the loop when the %boolean statement is false OR if you use %break

While program tic loops = 0; while(toc<5) loops = loops+1; disp(['number of loops = ', num2str(loops)]); disp(['number of seconds = ', num2str(toc)]); end

While program stopping after 10 loops tic loops = 0; while(toc<5) loops = loops+1; disp(['number of loops = ', num2str(loops)]); disp(['number of seconds = ', num2str(toc)]); if(loops>=10) break; end