Review questions for prelim 2

  1. allInterval

    function B = allInterval(x,a,b)
% x is a length-n vector.
% B is assigned the value of 1 (true) if every x-value is in the
%   interval [a,b].
% B is assigned the value of 0 (false) if at least one of the x-values
%   is not in the interval [a,b].
% Your implementation should make effective use of a while-loop.

  2. TotalValue

    % Refer to the Cost-Inventory application in Lecture 14.
% Complete the following function...

function T = totalValue(Inv,Cost)
% T is the total value of all the inventory in all the factories

  3. Censoring text

    function D = censor(str, A)
% Replace all occurrences of string str in character matrix A, regardless
% of case, with 'X's.
% A is a matrix of characters.
% str is a string.  Assume that str is never split across two lines in A.
% D is A with 'X's replacing the censored string str.
%
% Example:   A = ['Use MATLAB  '; ...
%                 'in that lab.']
%
%   and      str = 'lab'
%
%   Then     D = ['Use MATXXX  '; ...
%                 'in that XXX.']
%
% Hint: function strcmpi does case-insensitive comparison of two strings.
% Examples:  strcmpi('LAB', 'lab') returns true
%            strcmpi('LAB', 'LA')  returns false

  4. TwoClicks

    % Refer to Lecture 14 and the function RandomLinks(n).

A = RandomLinks(1000);

% Note that if A(i,j) is one, then there is a link on webpage j
% to webpage i. Write a fragment that prints "yes" if it is
% possible to go from web page #100 to webpage #200 in one or two clicks.
% Thus, if A(101,100) = 1 and A(200,101) = 1 then "yes".

  5. Checking for numbers in a vector/matrix

    function B = vecHasNegAndPos(x)
% x is a length-n vector and n>=2
% B is assigned the value of 1 (true) if x has at least one component
%   that is strictly negative and at least one component that is
%   strictly positive.
% Otherise B should be assigned the value of 0.
% Your implementation should make effective use of a while-loop.
    function B = matHasNegAndPos(A)
% A is an m-by-n real array with M>=2 and n>=2
% B is assigned the value of 1 (true) if A has at least one component
%   that has a strictly negative value and at least one component that has a
%   strictly positive value.
% Otherise B should be assigned the value of 0.
% Your implemention should make effective use of VecHasNegAndPos

  6. Reduce

    function B = Reduce(A)
% A is an n-by-n array with n odd and at least 3 in value.
% B is obtained by deleting all the even-indexed rows and columns.
% Thus if
% A = [ 1  2  3  4  5 ;...
%       6  7  8  9 10 ;...
%      11 12 13 14 15 ;...
%      16 17 18 19 20 ;...
%      21 22 23 24 25 ]
% then
% B = [ 1  3  5;...
%      11 13 15;...
%      21 23 25]

  7. Longest

    function [len, ind] = longest(C)
% Find the longest string(s) in cell array C.
% C is an n-by-1 cell array of strings, n>=1.
% len is the length of the longest string in C.
% ind is a vector, possibly of length one, containing the index number(s) 
% of the string(s) with length len

  8. Questions from Insight