Ending a recursive function

Hi,

I am having a problem ending this function, it should end once it reaches back to the initial start value.

function out = mysequence(start,dec)
n = 0;
if start>0 && dec>0
    fprintf('%d ',start);
   % n = n+1
    start = start - dec;
    mysequence(start,dec);
 
elseif start>0 && dec<0
    fprintf('%d ',start);
    start = start - dec;
    mysequence(start,dec);
    
elseif start<=0 
    fprintf('%d ',start);
    flag = 1;
    start = start + dec;
    mysequence(start,-dec);
end
 
 
end

[Walter Roberson]

if start>0 && dec>0
    fprintf('%d ',start);
   % n = n+1
    start = start - dec;
    mysequence(start,dec);
 
elseif start>0 && dec<0
    fprintf('%d ',start);
    start = start - dec;
    mysequence(start,dec);

What is the difference between those two cases, other than the commented out n = n + 1 ?

You return out from the function, but you never define out .

You have variables n and flag but you do not appear to use them.

it should end once it reaches back to the initial start value.

    function out = mysequence(start,dec,initialstart)
        if ~exist('initialstart', 'var')
            initialstart = start;
        end
        if start>0
        fprintf('%d ',start);
        start = start - dec;
        if start ~= initialstart
           out = mysequence(start,dec,initialstart);
        else
            out = shrug_you_are_not_clear_on_that;
        end
    end

[Anirudh Agarwala]

Thanks, for the option, but what if I just need two inputs, can I still store the inital start in anything?

Answer 1

[Star Strider]

I have not run your posted code, however two things are immediately apoparent.

First, in the calls to ‘mysequence’, the function calls are not assigning the output to any variable, so that result never gets passed to the function as a variable it can use, other than as as ‘ans‘, that it apparently never uses.

Second, the function calling itself could lead to an infinite recursion (or at least to the MATLAB recursion limit).

Neither of these will likely produce produce the desired result.