More help with probability...

Hey, so I fixed the first part of this code, but now the for loop where I use "strcmpi" is not working properly. It's only accounting for "peach' and my peach_count returns 100000 and the other fruits are 0. It's really weird because my function works fine.

    function x = produce
    A = 1e5;
    B = rand;
    C = ceil(A*B);
    if (C>=1 && C<= 20000);
        C = 'peach';
    elseif (C>= 20001 && C<= 55000);
        C = 'panana';
    elseif (C >= 55001);
        C = 'papaya';
    end 
    x = C 

    clc; clear all; 
    peach_count = 0; panana_count = 0; papaya_count = 0;
    N = 1e6;
    for k = 1:N
       fruit = produce;
       if strcmpi(fruit,'peach')
          peach_count = peach_count + 1;
       elseif strcmpi(fruit, 'panana')
           panana_count = panana_count + 1;
       elseif strcmpi(fruit, 'papaya')
           papaya_count = papaya_count + 1;
       end
    end

What am I doing wrong??

[Matt Kindig]

Strange...your code works correctly for me. Have you tried just restarting Matlab and re-running it?

[Nadia]

It runs correctly, however it's not correctly distributing the results in the for loop. I cleared the bottom section and only worked with the function and sure enough, when I type produce to see what it returns, it returns 'peach' every time even though that's not the correct answer.

[Matt Kindig]

Again, that's strange because I tried your entire code (both the function produce and the for loop), and I got reasonable counts for peach_count, papaya_count, and panana_count. When I called 'produce' several times, I get various values of 'peach', 'papaya', and 'pananan'.

Is it possible that you have multiple definitions of 'produce' somewhere? What does:

which produce
whos produce

give you?

[Nadia]

This is so strange. Which produce gives me my user name for the computer. Whos produce gave me nothing. I just decided to start over and copy this code back into matlab and now it says the my 'fruit = produce' line is invalid...I don't what I'm doing wrong. I'll try to play with it a bit more.

[Matt Kindig]

To explain a little bit about why I was having you do those commands:

• 'which produce' indicates the path to the produce.m file. I was specifically curious whether you had multiple 'produce.m' files on your path, which your results indicate you do not.
• 'whos produce' indicates information about any variables 'produce' in your workspace. I had thought that perhaps you had a variable called 'produce' as well, which was overriding the function call. However, the fact that the whos command returned nothing indicates this is not the case.

I must admit that I'm stumped. Are you putting the function into a separate file as the script? In other words, you should have two different m-files:

=== produce.m

   function C = produce
      A = 1e5;
      B = rand;
      C = ceil(A*B);
      if (C>=1 && C<= 20000);
          C = 'peach';
      elseif (C>= 20001 && C<= 55000);
          C = 'panana';
      elseif (C >= 55001);
          C = 'papaya';
      end

=== main.m (or some other name)

   clc; clear; 
      peach_count = 0; panana_count = 0; papaya_count = 0;
      N = 1e6;
      for k = 1:N
         fruit = produce;
         if strcmpi(fruit,'peach')
            peach_count = peach_count + 1;
         elseif strcmpi(fruit, 'panana')
             panana_count = panana_count + 1;
         elseif strcmpi(fruit, 'papaya')
             papaya_count = papaya_count + 1;
         end
      end

[Nadia]

@Matt Kindig thanks so much!! I hadn't put them in separate m-files. Such a silly mistake, but thanks again!

Answer 1

[Ahmed A. Selman]

Just pay attention to how you use function call inside a program. Either you have two files as stated above, or use one main (calling function) which contains another (inner) function as:

% This is the main (calling) function
function output=firstFunction
    peach_count = 0; panana_count = 0; papaya_count = 0;
    N = 1e6;
    for k = 1:N
       fruit = produce;
       if strcmpi(fruit,'peach')
          peach_count = peach_count + 1;
       elseif strcmpi(fruit, 'panana')
           panana_count = panana_count + 1;
       elseif strcmpi(fruit, 'papaya')
           papaya_count = papaya_count + 1;
       end
    end
    output=[peach_count;panana_count;papaya_count];

 % Here is the inner function 
  function x = produce
      A = 1e5;
      B = rand;
      C = ceil(A*B);
      if (C>=1 && C<= 20000);
          C = 'peach';
      elseif (C>= 20001 && C<= 55000);
          C = 'panana';
      elseif (C >= 55001);
          C = 'papaya';
      end 
      x = C;

So, when you run:

 OutPut=firstFunction
 OutPut=

        200191
        349241
        450568

Note: The output varies since it's based on a random creation.

Regards

[Nadia]

Thanks so much!!!