[{"id":1,"question":"From what distribution does the `rand()` function return value?","code":"","reference":"","choices":[{"text":"normal","answer":false,"code":false},{"text":"poisson","answer":false,"code":false},{"text":"binomial","answer":false,"code":false},{"text":"uniform","answer":true,"code":false}]},{"id":2,"question":"Based on the code below, c is the _ of a.","code":"a = rand(1, 11); b = sort(a); c = b(1, ceil(end/2));","reference":"```","choices":[{"text":"median","answer":true,"code":false},{"text":"mode","answer":false,"code":false},{"text":"mean","answer":false,"code":false},{"text":"margin","answer":false,"code":false}]},{"id":3,"question":"What does the Profiler track?","code":"","reference":"","choices":[{"text":"execution time","answer":true,"code":false},{"text":"command history","answer":false,"code":false},{"text":"errors","answer":false,"code":false},{"text":"the value of variables","answer":false,"code":false}]},{"id":4,"question":"Which code block contains the correct syntax for a `while` loop?","code":"a = 0; do a = a + 1; while a < 5 end a = 0; while(a < 5) a = a + 1; a = 0; while a < 5: a = a + 1; a = 0; while a < 5 a = a + 1; end","choices":[{"text":"\na = 0;\ndo\n a = a + 1;\nwhile a < 5\nend\n","code":true,"answer":false},{"text":"\na = 0;\nwhile(a < 5)\n a = a + 1;\n","code":true,"answer":false},{"text":"\na = 0;\nwhile a < 5:\n a = a + 1;\n","code":true,"answer":false},{"text":"\na = 0;\nwhile a < 5\n a = a + 1;\nend\n","code":true,"answer":true}]},{"id":5,"question":"What does `b` contain?","code":"a = 19 20 12 0 6 6 9 56 0 3 46 8 9 8 19 9 8 8 19 46 1 9 46 6 19 b = 56 0 9 8 b = 8 19 19 46","choices":[{"text":"\nb =\n\n 56 0\n 9 8\n","code":true,"answer":true},{"text":"\nb =\n\n 8 19\n 19 46\n","code":true,"answer":false}]},{"id":6,"question":"You have written a function `myfun` and want to measure how long it takes to run. Which code segment will return in `t` the time in seconds it takes `myfun` to run?","code":"t = cputime(myfun()); tic; myfun(); toc; timer.start; myfun() t = timer.stop; t = timer(myfun());","choices":[{"text":"\nt = cputime(myfun());\n","code":true,"answer":false},{"text":"\ntic;\nmyfun();\ntoc;\n","code":true,"answer":true},{"text":"\ntimer.start;\nmyfun()\nt = timer.stop;\n","code":true,"answer":false},{"text":"\nt = timer(myfun());\n","code":true,"answer":false}]},{"id":7,"question":"What is `%%` used for?","code":"","reference":"","choices":[{"text":"argument placeholder","answer":false,"code":false},{"text":"block quotes","answer":false,"code":false},{"text":"code sections","answer":true,"code":false},{"text":"conversion specifier","answer":false,"code":false}]},{"id":8,"question":"what is the `.` character NOT used for?","code":"","reference":"","choices":[{"text":"structure field access","answer":false,"code":false},{"text":"a decimal point","answer":false,"code":false},{"text":"cell array access","answer":true,"code":false},{"text":"element-wise operations","answer":false,"code":false}]},{"id":9,"question":"Which function could you use for multiple linear regression?","code":"","reference":"","choices":[{"text":"polyval","answer":false,"code":false},{"text":"regress","answer":true,"code":false},{"text":"solve","answer":false,"code":false},{"text":"polyfit","answer":false,"code":false}]},{"id":10,"question":"For which of these arrays do `mean`, `median`, and `mode` return the same value?","code":"","reference":"","choices":[{"text":"[0 1 1 1 2]","answer":true,"code":false},{"text":"[1 3 5 5 6]","answer":false,"code":false},{"text":"[0 1 1 1 1]","answer":false,"code":false},{"text":"[0 0 5 5 5]","answer":false,"code":false}]},{"id":11,"question":"You are in the middle of a long MATLAB session where you have performed many analyses and made many plots. You run the following commands, yet a figure window doesn't pop up on the top of your screen with your plot. What might be the issue?","code":"x = [-1:0.1:1]; y = X.^2; plot(x, y)","reference":"```","choices":[{"text":"Your plot doesn't plot in a figure window because `figure` was not called immediately in advance.","answer":false,"code":false},{"text":"Your `plot` syntax is incorrect.","answer":false,"code":false},{"text":"Your plot is in a figure window that was already open, hidden behind other windows on your screen.","answer":true,"code":false},{"text":"Your plot was saved to an image file but not displayed.","answer":false,"code":false}]},{"id":12,"question":"How do you access the value for the field `name` in structure S?","code":"","reference":"","choices":[{"text":"S['name']","answer":false,"code":false},{"text":"S.name","answer":true,"code":false},{"text":"S('name')","answer":false,"code":false},{"text":"S{'name'}","answer":false,"code":false}]},{"id":13,"question":"What built-in definition does i have?","code":"","reference":"","choices":[{"text":"basic imaginary unit","answer":true,"code":false},{"text":"index function","answer":false,"code":false},{"text":"infinity","answer":false,"code":false},{"text":"index variable","answer":false,"code":false}]},{"id":14,"question":"Which statement is equivalent to this for loop?","code":"a = [1 2 3; 4 5 6]; b = zeros(size(a)); for i_row = 1:size(a, 1) for i_col = 1:size(a, 2) b(i_row, i_col) = a(i_row, i_col)^2; end end","reference":"```","choices":[{"text":"b = a*a;","answer":false,"code":false},{"text":"b = a.^2;","answer":true,"code":false},{"text":"b = a^2;","answer":false,"code":false},{"text":"b = pow2(a);","answer":false,"code":false}]},{"id":15,"question":"You have plotted values of cosine from -10 to 10 and want to change the x-axis tick marks to every pi, from -3*pi to 3*pi. Which statement will do that?","code":"","reference":"","choices":[{"text":"xticks(-3*pi:3.14:3*pi)","answer":false,"code":false},{"text":"xticks(-3*pi:pi:3*pi)","answer":true,"code":false},{"text":"xticks(linespace(-3*pi(), 3*pi(), pi()))","answer":false,"code":false},{"text":"xticks(linespace(-3*pi, 3*pi, pi)","answer":false,"code":false}]},{"id":16,"question":"What is the value of `c`?","code":"a = ones(1,3); b = 1:3; c = conv(a,b)","reference":"```","choices":[{"text":"[-1 2 -1]","answer":false,"code":false},{"text":"[1 3 6 5 3]","answer":true,"code":false},{"text":"6","answer":false,"code":false},{"text":"[1 -2 1]","answer":false,"code":false}]},{"id":17,"question":"Which function CANNOT be used to randomly sample data?","code":"","reference":"","choices":[{"text":"datasample","answer":false,"code":false},{"text":"randi","answer":false,"code":false},{"text":"resample","answer":true,"code":false},{"text":"randperm","answer":false,"code":false}]},{"id":18,"question":"Which choice is correct syntax for a `switch` statement?","code":"x = 7; switch x case 2 disp(\"two\"); otherwise disp(\"not two\"); end x = 7; switch x : case 2 disp(\"two\"); otherwise disp(\"not two\"); end x = 7; switch x case 2 disp(\"two\"); else disp(\"not two\"); end x = 7; switch x case 2 disp(\"two\"); default disp(\"not two\"); end","choices":[{"text":"\nx = 7;\nswitch x\n case 2\n disp(\"two\");\n otherwise\n disp(\"not two\");\nend\n","code":true,"answer":true},{"text":"\nx = 7;\nswitch x :\n case 2\n disp(\"two\");\n otherwise\n disp(\"not two\");\nend\n","code":true,"answer":false},{"text":"\nx = 7;\nswitch x\n case 2\n disp(\"two\");\n else\n disp(\"not two\");\nend\n","code":true,"answer":false},{"text":"\nx = 7;\nswitch x\n case 2\n disp(\"two\");\n default\n disp(\"not two\");\nend\n","code":true,"answer":false}]},{"id":19,"question":"What is the result of this code?","code":"a = 1; b = 2; c = 3; d = 4; e = c / (~a - b == c - d); c = NaN c = Inf c = -0.2500","choices":[{"text":"\nc =\n NaN\n","code":true,"answer":false},{"text":"\nc =\n Inf\n","code":true,"answer":true},{"text":"\nc =\n -0.2500\n","code":true,"answer":false}]},{"id":20,"question":"What is true of a handle class object?","code":"","reference":"","choices":[{"text":"When you pass a handle object to a function, a new object is made that is independent of the original.","answer":false,"code":false},{"text":"All copies of handle objects refer to the same underlying object.","answer":true,"code":false},{"text":"Handle object cannot reference one another.","answer":false,"code":false},{"text":"Handle object do not have a default `eq` function.","answer":false,"code":false}]},{"id":21,"question":"Which choice has a different final result in `f10` than the other three?","code":"f10 = 1; for i = 1:10 f10 = f10 * i; end `f10 = factorial(10)` MATLAB f10 = 1; i = 1; while i <= 10 i = i + 1; f10 = i * f10; end `f10 = prod(1:10)`","choices":[{"text":"\nf10 = 1;\nfor i = 1:10\n f10 = f10 * i;\nend\n","code":true,"answer":false},{"code":true,"answer":false},{"text":"MATLAB\nf10 = 1;\ni = 1;\nwhile i <= 10\n i = i + 1;\n f10 = i * f10;\nend\n","code":true,"answer":true},{"code":true,"answer":false}]},{"id":22,"question":"Which choice will NOT give you a 5 x 5 identity matrix?","code":"a = rand(5); round(a * inv(a)) `diag(ones(5, 1))` `identity(5)` `eye(5)`","choices":[{"text":"\na = rand(5);\nround(a * inv(a))\n","code":true,"answer":false},{"code":true,"answer":false},{"code":true,"answer":true},{"code":true,"answer":false}]},{"id":23,"question":"Which statement creates this structure?","code":"dog = name: 'Bindy' breed: 'border collie' weight: 32 `dog = struct('name', 'Bindy'; 'breed', 'border collie'; 'weight', 32);` dog.name = 'Bindy'; dog.breed = 'border collie'; dog.weight = 32; dog = { 'name' : 'Bindy', 'breed' : 'border collie', 'weight': 32; } dog('name') = 'Bindy'; dog('breed') = 'border collie'; dog('weight') = 32;","choices":[{"code":true,"answer":false},{"text":"\ndog.name = 'Bindy';\ndog.breed = 'border collie';\ndog.weight = 32;\n","code":true,"answer":true},{"text":"\ndog = {\n 'name' : 'Bindy',\n 'breed' : 'border collie',\n 'weight': 32;\n}\n","code":true,"answer":false},{"text":"\ndog('name') = 'Bindy';\ndog('breed') = 'border collie';\ndog('weight') = 32;\n","code":true,"answer":false}]},{"id":24,"question":"`my_func` is a function as follows. What is the value of `a` at the end of the code beneath?","code":"function a = my_func(a) a = a + 1; end a = 0; for i = 1:3 my_func(a); end a = my_func(a);","reference":"```","choices":[{"answer":false,"code":false},{"text":"4","answer":false,"code":false},{"text":"3","answer":false,"code":false},{"text":"0","answer":false,"code":false},{"text":"1","answer":true,"code":false}]},{"id":25,"question":"Which statement could create this cell array?","code":"c = {[\"hello world\"]} {1×1 cell} {[\"goodbye\"]} {1×3 double}","reference":"```","choices":[{"text":"c = {\"hello world\" {\"hello\"} \"goodbye\" [1 2 ]};","answer":false,"code":false},{"text":"c = {\"hello world\" {\"hello\"} \"goodbye\" {[1 2 3]}};","answer":false,"code":false},{"text":"c = {\"hello world\" {\"hello\"} \"goodbye\" [1 2 3]};","answer":true,"code":false},{"text":"c = {\"hello world\" {\"hello\" \"hello\"} \"goodbye\" {[1 2 3]}};","answer":false,"code":false}]},{"id":26,"question":"Which choice adds `b` to each row of `a`?","code":"a = ones(4, 4); b= [1 2 3 4];","reference":"```","choices":[{"text":"a = a + reshape(b, 4, 1);","answer":false,"code":false},{"text":"a = a + b';","answer":false,"code":false},{"text":"a = a + repmat(b, 4, 1);","answer":true,"code":false},{"text":"a = a + [b b b b];","answer":false,"code":false}]},{"id":27,"question":"Which choice replaces all `a`s with `o`s?","code":"for i = 1:length(fruit) fruit{i}(fruit{i} == a) == o; end for i = 1:length(fruit) fruit(i)(fruit(i) == 'a') == 'o'; end for i = 1:length(fruit) fruit{i}(fruit{i} == 'a') == 'o'; end for i = 1:length(fruit) fruit{i}(fruit{i} == 'a') == 'o';","choices":[{"text":"\nfor i = 1:length(fruit)\n fruit{i}(fruit{i} == a) == o;\nend\n","code":true,"answer":false},{"text":"\nfor i = 1:length(fruit)\n fruit(i)(fruit(i) == 'a') == 'o';\nend\n","code":true,"answer":false},{"text":"\nfor i = 1:length(fruit)\n fruit{i}(fruit{i} == 'a') == 'o';\nend\n","code":true,"answer":true},{"text":"\nfor i = 1:length(fruit)\n fruit{i}(fruit{i} == 'a') == 'o';\n","code":true,"answer":false}]},{"id":28,"question":"Which statement returns the roots for the polynomial `x^2 + 2x - 4`?","code":"","reference":"","choices":[{"text":"poly([1 2 -4])","answer":false,"code":false},{"text":"solve(x^2 + 2x - 4 == 0)","answer":false,"code":false},{"text":"polyfit(x^2 + 2x - 4 == 0)","answer":false,"code":false},{"text":"roots([1 2 -4])","answer":true,"code":false}]},{"id":29,"question":"Which choice is the proper syntax to append a new elements `a` to the end of 1x 2 dimensional cell array `C`?","code":"","reference":"","choices":[{"text":"C = {C a};","answer":false,"code":false},{"text":"C = cellcat(C a)","answer":false,"code":false},{"text":"C = cat(2, {a}, C)","answer":false,"code":false},{"text":"C{end+1}=a","answer":true,"code":false}]},{"id":30,"question":"You have loaded a dataset of people's heights into a 100 x 1 array called `height`. Which statement will return a 100 x 1 array, `sim_height`, with values from a normal distribution with the same mean and variance as your height data?","code":"","reference":"","choices":[{"text":"sim_height = std(height) + mean(height) * randn(100, 1);","answer":false,"code":false},{"text":"sim_height = mean(height) + std(height) * randn(100, 1);","answer":true,"code":false},{"text":"sim_height = randn(std(height), mean(height), [100, 1]);","answer":false,"code":false},{"text":"sim_height = randn(mean(height), std(height), [100, 1]);","answer":false,"code":false}]},{"id":31,"question":"Which statement returns a cell array of the strings containing '`burger`' from `menu`?","code":"`menu = {'hot dog' 'corn dog' 'regular burger' 'cheeseburger' 'veggie burger'}`","reference":"`menu = {'hot dog' 'corn dog' 'regular burger' 'cheeseburger' 'veggie burger'}`","choices":[{"text":"menu{strfind(menu, 'burger')}","answer":false,"code":false},{"text":"menu(strfind(menu, 'burger'))","answer":false,"code":false},{"text":"menu{contains(menu, 'burger')}","answer":false,"code":false},{"text":"menu(contains(menu, 'burger'))","answer":true,"code":false}]},{"id":32,"question":"What is the set of possible values that `a` may contain?","code":"a = randi(10, [1, 10]); a(3) = 11; a(a>2) = 12;","reference":"```","choices":[{"text":"3, 4, 5, 6, 7, 8, 9, 10, 11, 12","answer":false,"code":false},{"text":"1, 2, 12","answer":true,"code":false},{"text":"2, 11, 12","answer":false,"code":false},{"text":"1, 12","answer":false,"code":false}]},{"id":33,"question":"Which statement is true about the sparse matrices?","code":"","reference":"","choices":[{"text":"You can use the `sparse` function to remove empty cells from cell array variables.","answer":false,"code":false},{"text":"Sparse matrices always use less memory than their associated full matrices.","answer":true,"code":false},{"text":"Mixtures of sparse and full matrices can be combined in all of MATLAB's built-in arithmetic operations.","answer":false,"code":false},{"text":"The `sparse` function requires its input to be a full matrix with at least 50% zero elements.","answer":false,"code":false}]},{"id":34,"question":"Which statement using logical indices will result in an error?","code":"`a = 1:10;`","reference":"`a = 1:10;`","choices":[{"text":"b = a(a ~= 11)","answer":false,"code":false},{"text":"b = a(a == 1)","answer":false,"code":false},{"text":"b = a(a>6 && a<9)","answer":true,"code":false},{"text":"b = a(a | 1)","answer":false,"code":false}]},{"id":35,"question":"Which statement turns `menu` into the variable `menu_string` below?","code":"menu = {'hot dog' 'corn dog' 'regular burger' 'cheeseburger' 'veggie burger'} menu_string = 'hot dog corn dog regular burger cheeseburger veggie burger'","reference":"```","choices":[{"text":"menu_string = cell2mat(join(menu, newline))","answer":true,"code":false},{"text":"menu_string = cell2mat(join(menu, 'n'))","answer":false,"code":false},{"text":"menu_string = join(menu, newline)","answer":false,"code":false},{"text":"menu_string = cell2mat(pad(menu))","answer":false,"code":false}]},{"id":36,"question":"Which code snippet sets a new random seed based on the current time and saves the current settings of the random number generator?","code":"`rng_settings_curr = rng('shuffle');` rng(time()); rng_settings_curr = rng(); `rng_settings_curr = rand('shuffle');` rng('shuffle'); rng_settings_curr = rng();","choices":[{"code":true,"answer":true},{"text":"\nrng(time());\nrng_settings_curr = rng();\n","code":true,"answer":false},{"code":true,"answer":false},{"text":"\nrng('shuffle');\nrng_settings_curr = rng();\n","code":true,"answer":false}]},{"id":37,"question":"You have a matrix `data` in which each column is mono audio recording from a room in your house. You've noticed that each column has a very different mean and when you plot them all on the same graph, the spread across the y axis make it impossible to see anything. You want to subtract the mean from each column. Which code block will accomplish this?","code":"`data_nomean = data - repmat(median(data), size(data, 1), 1);` `data_nomean = bsxfun(@minus, data, mean(data));` data_nomean = zeros(size(data)); for i = 1:size(data, 1) data_nomean(i, :) = data(i, :) - mean(data(i, :)); end `data_nomean = zscore(data');`","choices":[{"code":true,"answer":false},{"code":true,"answer":true},{"text":"\ndata_nomean = zeros(size(data));\nfor i = 1:size(data, 1)\n data_nomean(i, :) = data(i, :) - mean(data(i, :));\nend\n","code":true,"answer":false},{"code":true,"answer":false}]},{"id":38,"question":"Which code block results in an array `b` containing the mean values of each array within `C`?","code":"b = zeros(1, size(C, 2)); for i_C = 1:size(C, 2) b(i_C) = mean(C(i_C)); end `b = cellfun(@mean, C);` b = zeros(1, size(C, 1)); for i_C = 1:size(C, 1) b(i_C) = mean(C{i_C}(:)); end `b = cellfun(@(m) mean(m(:)), C)`","choices":[{"text":"\nb = zeros(1, size(C, 2));\nfor i_C = 1:size(C, 2)\n b(i_C) = mean(C(i_C));\nend\n","code":true,"answer":false},{"code":true,"answer":false},{"text":"\nb = zeros(1, size(C, 1));\nfor i_C = 1:size(C, 1)\n b(i_C) = mean(C{i_C}(:));\nend\n","code":true,"answer":false},{"code":true,"answer":true}]},{"id":39,"question":"Which statement creates a logical array that is 1 if the element in `passwords` contains a digit and 0 if it does not?","code":"`passwords = {'abcd' '1234' 'qwerty' 'love1'};`","reference":"`passwords = {'abcd' '1234' 'qwerty' 'love1'};`","choices":[{"text":"contains(password, 'd')","answer":false,"code":false},{"text":"~isempty(regexp(passwords, 'd'))","answer":false,"code":false},{"text":"cellfun(@(x) ~isempty(regexp(x, 'd')), passwords)","answer":true,"code":false},{"text":"regexp(passwords, 'd')","answer":false,"code":false}]},{"id":40,"question":"Which is NOT a function that adds text to a plot?","code":"","reference":"","choices":[{"text":"title","answer":false,"code":false},{"text":"text","answer":false,"code":false},{"text":"label","answer":true,"code":false},{"text":"legend","answer":false,"code":false}]},{"id":41,"question":"Which code block most likely produced this graph?","code":"![MatLab Q39](images/matlab_Q39.jpg) figure x = rand(10,10); r = corrcoef(x); surf(r) colorbar figure x = rand(10,10); r = corrcoef(x); imagesc(r) colorbar","choices":[{"text":"\nfigure\nx = rand(10,10);\nr = corrcoef(x);\nsurf(r)\ncolorbar\n","code":true,"answer":false},{"text":"\nfigure\nx = rand(10,10);\nr = corrcoef(x);\nimagesc(r)\ncolorbar\n","code":true,"answer":true}]},{"id":42,"question":"What kind of files are stored with the .mat extension?","code":"","reference":"","choices":[{"text":"figure files","answer":false,"code":false},{"text":"script files","answer":false,"code":false},{"text":"function files","answer":false,"code":false},{"text":"stored variable files","answer":true,"code":false}]},{"id":43,"question":"You would like to randomly reorder every element in array a and put the result into another array b. Which code is NOT necessary to do that?","code":"`a = 1:10;` `b = a(randi(10, 1, 10));` m = perms(a); i = randi(factorial(10), 1); b = a(m(i, :)) b = a(i); b = a(randperm(10));","choices":[{"code":true,"answer":true},{"text":"\nm = perms(a);\ni = randi(factorial(10), 1);\nb = a(m(i, :))\n","code":true,"answer":false},{"text":"\n[s, j] = sort(rand(10, 1));\nb = a(i);\n","code":true,"answer":false},{"text":"\nb = a(randperm(10));\n","code":true,"answer":false}]},{"id":44,"question":"Which statement returns **1** (true)?","code":"a = 'stand' b = \"stand\"","reference":"```","choices":[{"text":"a == b","answer":true,"code":false},{"text":"ischar(b)","answer":false,"code":false},{"text":"length(a) == length(b)","answer":false,"code":false},{"text":"class(a) == class(b)","answer":false,"code":false}]},{"id":45,"question":"Which does E contain?","code":"C = {'dog' 'cat' 'mouse'} D = {'cow' 'piranha' 'mouse'} E = setdiff(C,D)","reference":"```","choices":[{"text":"E = {'cat'} {'dog'}","answer":true,"code":false},{"text":"E = {'mouse'}","answer":false,"code":false},{"text":"E = {'cat'} {'cow'} {'dog'} {'piranha'}","answer":false,"code":false},{"text":"E =","answer":false,"code":false}]},{"id":46,"question":"Where in the UI can you see what variables have been created, their values, and their class?","code":"","reference":"","choices":[{"text":"Editor","answer":false,"code":false},{"text":"command window","answer":false,"code":false},{"text":"details","answer":false,"code":false},{"text":"workspace","answer":true,"code":false}]},{"id":47,"question":"Given the following x and y coordinates, which choice calculates a linear regression for the x and y coordinates, and which plots the points of the x,y data and the regression line on the same graph?","code":"x = 9.0646 6.4362 7.8266 8.3945 5.6135 4.8186 2.8862 10.9311 1.1908 3.2586 y = 15.4357 11.0923 14.1417 14.9506 8.7687 8.0416 5.1662 20.5005 1.0978 coeff_line = polyfit(x,y,1) x_line = floor(min(x)):0.1:ceil(max(x)); y_line = polyval(coeff_line,x_line) figure; plot(x,y,'o') hold on plot(x_linemy_line) figure plot(x,y,'o') coeff_line = polyfit(x,y,1); x_line = floor(min(x)):0.1:ceil(max(x)); y_line = polyval(coeff_line,x_line); plot(x_line,y_line) figure plot(x,y) coeff_line = polyfit(x,y,1); x_line = floor(min(x)):0.1:ceil(max(x)); y_line = polyval(coeff_line,x_line); hold on; plot(x_line,y_line) coeff_line = polyfit(x,y,1); x_line = floor(min(x)):0.1:ceil(max(x)); y_line = polyval(coeff_line,x_line); figure; plot(x,y,'o') hold on plot(x_line,y_line)","choices":[{"text":"\ncoeff_line = polyfit(x,y,1)\nx_line = floor(min(x)):0.1:ceil(max(x));\ny_line = polyval(coeff_line,x_line)\n\nfigure; plot(x,y,'o')\nhold on\nplot(x_linemy_line)\n","code":true,"answer":true},{"text":"\nfigure\nplot(x,y,'o')\n\ncoeff_line = polyfit(x,y,1);\nx_line = floor(min(x)):0.1:ceil(max(x));\ny_line = polyval(coeff_line,x_line);\nplot(x_line,y_line)\n","code":true,"answer":false},{"text":"\nfigure\nplot(x,y)\n\ncoeff_line = polyfit(x,y,1);\nx_line = floor(min(x)):0.1:ceil(max(x));\ny_line = polyval(coeff_line,x_line);\nhold on; plot(x_line,y_line)\n","code":true,"answer":false},{"text":"\ncoeff_line = polyfit(x,y,1);\nx_line = floor(min(x)):0.1:ceil(max(x));\ny_line = polyval(coeff_line,x_line);\n\nfigure; plot(x,y,'o')\nhold on\nplot(x_line,y_line)\n","code":true,"answer":false}]},{"id":48,"question":"If you run this piece of code, you will get an error. Why?","code":"a = [0 1 2 3; 4 5 6 7]; a = a^2;","reference":"```","choices":[{"text":"You are attempting to multiply a non-square matrix by itself, causing a dimension mismatch.","answer":true,"code":false},{"text":"MATLAB does not allow you to square all the elements in the matrix in a single operation.","answer":false,"code":false},{"text":"You must use the ** operator instead of the ^ operator.","answer":false,"code":false},{"text":"You cannot square matrices that have a 0 as the first element.","answer":false,"code":false}]},{"id":49,"question":"Which command will create a 10-element vector v with values from 1 to 10?","code":"","reference":"","choices":[{"text":"v = {1:10}","answer":false,"code":false},{"text":"v = [1-10]","answer":false,"code":false},{"text":"v = 1:10","answer":true,"code":false},{"text":"v = (10)","answer":false,"code":false}]},{"id":50,"question":"For a 5 x 5 array, the two subscript index (4,2) indexes the same location as linear index `___`.","code":"","reference":"","choices":[{"text":"7","answer":false,"code":false},{"text":"8","answer":false,"code":false},{"text":"17","answer":false,"code":false},{"text":"9","answer":true,"code":false}]},{"id":51,"code":"","reference":"","choices":[{"text":"Global variables have a higher performance overhead than persistent variables.","answer":false,"code":false},{"text":"Global variables remain in memory after clear all; persistent variables do not.","answer":false,"code":false},{"text":"Global variables can be used to cache data in memory; persistent variables cannot.","answer":false,"code":false},{"text":"Global variables are accessible outside the function scope; persistent variables are not.","answer":true,"code":false}]},{"id":52,"question":"How is the random seed for MATLAB's random number generator first initializedin a MATLAB Session?","code":"","reference":"","choices":[{"text":"Seed is undefined until it is initialized by the user.","answer":false,"code":false},{"text":"Seed is set to a value based on the current time when user first calls rand()","answer":false,"code":false},{"text":"Seed is set to a value based on the current time on startup.","answer":false,"code":false},{"text":"Seed is set to a static default value on startup.","answer":true,"code":false}]},{"id":53,"question":"At what will MATLAB look first for a called function?","code":"","reference":"","choices":[{"text":"functions on the path","answer":false,"code":false},{"text":"built-in functions","answer":false,"code":false},{"text":"functions within the current file","answer":false,"code":false},{"text":"functions within the current directory","answer":false,"code":false}]},{"id":54,"question":"Which choice is the correct syntax for declaring a function that returns the input value as the output?","code":"function mystery_func(a) : return a function b = mystery_func(a) b = a; end def b = mystery_func(a) b = a; end function mystery_func(a) b = a; return b; end","choices":[{"text":"\nfunction mystery_func(a) :\n return a\n","code":true,"answer":false},{"text":"\nfunction b = mystery_func(a)\n b = a;\nend\n","code":true,"answer":true},{"text":"\ndef b = mystery_func(a)\n b = a;\nend\n","code":true,"answer":false},{"text":"\nfunction mystery_func(a)\n b = a;\n return b;\nend\n","code":true,"answer":false}]},{"id":55,"question":"What is the state of a at the end of this code?","code":"a = [1 2; 3 4]; b = a(:,2); c = b + 3; a(1:2,1) = c; a = 6 3 7 4 a = 5 2 7 4 a = 5 7 a = 6 7","choices":[{"text":"\na =\n 5 2\n 7 4\n","code":true,"answer":false},{"text":"\na =\n 5\n 7\n","code":true,"answer":true},{"text":"\na =\n 6\n 7\n","code":true,"answer":false},{"code":true,"answer":false}]},{"id":56,"question":"You've just plotted some data and want to change the color behind the lines you've plotted to black. Which code block will accomplish this?","code":"","reference":"","choices":[{"text":"`h_f = figure; set(h_f,'Color', [0 0 0]);`","answer":false,"code":false},{"text":"`h_a = gca; set(h_a,'Color', [0 0 0]);`","answer":true,"code":false},{"text":"`h_a = axes; set(h_a,'Color', [0 0 0]);`","answer":false,"code":false},{"text":"`h_f = gcf; set(h_a,'Color', [0 0 0]);`","answer":false,"code":false}]},{"id":57,"question":"Which statement will return all the odd numbers from 1 to 9?","code":"","reference":"","choices":[{"text":"`2*[1:5]+1`","answer":false,"code":false},{"text":"`1:2:9`","answer":true,"code":false},{"text":"`isodd(1:9)`","answer":false,"code":false},{"text":"`1:odd:9`","answer":false,"code":false}]},{"id":58,"question":"In MATLAB, the `imfilter` command performs a convolution operation between an image and a matrix. Suppose you have an image loaded in MATLAB into the variable `img` and you apply the following code. The original image appears slightly blurred because the convolution smoothed out the image (removed noise). Why do you think this happened?","code":"h = ones(5,5)/25; imshow(imfilter(img,h));","reference":"```","choices":[{"text":"`h` is a Gaussian filter that adds to 1. Its intended effect is to highlight image edges.","answer":false,"code":false},{"text":"`h` is an averaging filter uniformly distributed that adds to 1. Its intended effect is to smooth out images (remove noise).","answer":true,"code":false},{"text":"`h` is a Laplacian filter that adds up to 0. Its intended effect is to smooth out images (remove noise).","answer":false,"code":false},{"text":"`imfilter` is a function that always blurs the images.","answer":false,"code":false}]},{"id":59,"question":"What is the size of `b`?","code":"a = [1 2 3]; b = repmat(a,2,3);","reference":"```","choices":[{"text":"1x3","answer":false,"code":false},{"text":"3x2","answer":false,"code":false},{"text":"2x3","answer":false,"code":false},{"text":"2x9","answer":true,"code":false}]},{"id":60,"question":"Which statement reverses vector `a`?","code":"a = [ 1 2 3 4];","reference":"```","choices":[{"text":"reverse(a)","answer":false,"code":false},{"text":"a(end:- 1:1)","answer":true,"code":false},{"text":"rev(a)","answer":false,"code":false},{"text":"a(::-1)","answer":false,"code":false}]},{"id":61,"question":"Which command will create a column vector with the values 7, 8, and 9?","code":"","reference":"","choices":[{"text":"`c = [7,8,9]`","answer":false,"code":false},{"text":"`c = [7: 8: 9]`","answer":false,"code":false},{"text":"`c = [7; 8; 9]`","answer":true,"code":false},{"text":"`c = [7 8 9]`","answer":false,"code":false}]},{"id":62,"question":"What do you call in the **command** window to see all the variables in the workspace and their classes?","code":"","reference":"","choices":[{"text":"`who`","answer":false,"code":false},{"text":"`vars`","answer":false,"code":false},{"text":"`whos`","answer":true,"code":false},{"text":"`who all`","answer":false,"code":false}]},{"id":63,"question":"You wrote a new function named `snap` in an m-file and when you call it, you're not getting the output you expect. You previously wrote a different function named `snap`, which you think might also be on the search path. Which command can you use to see if the old `snap` function is being called?","code":"","reference":"","choices":[{"text":"which","answer":true,"code":false},{"text":"who","answer":false,"code":false},{"text":"lookfor","answer":false,"code":false},{"text":"what","answer":false,"code":false}]},{"id":64,"question":"What is a reason to save a MAT-file using the `-v7.3` flag?","code":"","reference":"","choices":[{"text":"to ensure backward compatibility","answer":false,"code":false},{"text":"to avoid HDF5 overhead in MAT-file","answer":false,"code":false},{"text":"to include a variable greater that 2GB","answer":true,"code":false},{"text":"to use compression by default","answer":false,"code":false}]}]

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From what distribution does the `rand()` function return value?