save answers for different values used in a while loop in an array of (2,n)

Question

Harm 2014-10-15

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/158706-save-answers-for-different-values-used-in-a-while-loop-in-an-array-of-2-n

评论： David Sanchez 2014-10-15

the question is how to save the highest value of vector pnew(highestvalue) and the location of this highest value in the vector pnew (index) in a matrix of the size (2,plocation)?

I get the right values for column p when i only apply a while loop.

function  [amountofsteps, pnew, highestvalue, index]=exercise30b(p)
iter=1;
pnew=[];
k=1;
r=rem(p,2);
amountofsteps=1;
while (p>k)
    if (r==0)
        pnew(iter)=p/2;
    elseif (r>0) 
        pnew(iter)=p*3+1;
    end;
 p=pnew(iter);
 r=rem(p,2);
 amountofsteps=amountofsteps+1;
 iter=iter+1;
 [index, highestvalue]=max(pnew);
end;
disp(amountofsteps);
disp(pnew);
disp(highestvalue);
disp(index);

now i want to apply a for loop to derive the same for different values of p. Unfortunately, I get an error that "index" and "highest value" are undefined variables when i want to accomodate them into the array. please see below:

function  [answerarray]=opgave30c2(d)
for plocation=1:d
iter=1;
pnew=[];
k=1;
p=plocation;
r=rem(p,2);
amountofsteps=1;
answerarray=zeros(2,d);
while (p>k)
    if (r==0)
        pnew(iter)=p/2;
    elseif (r>0) 
        pnew(iter)=p*3+1;
    end;
   p=pnew(iter);
   r=rem(p,2);
   amountofsteps=amountofsteps+1;
   iter=iter+1;
  highestvalue=max(pnew);
  index = find(pnew == max(pnew), 1);
  end;
  answerarray(1,plocation)=index;
  answerarray(2,plocation)=highestvalue;
  clear m n pnew p aantalstappen iter highestvalue plocation
end;
% disp(aantalstappen);
% disp(pnew);
% disp(highestvalue);
% disp(index);
% disp(p);

Could you guys please help me out?

Thanks!

H

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Answer 1

David Sanchez 2014-10-15

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/158706-save-answers-for-different-values-used-in-a-while-loop-in-an-array-of-2-n#answer_155232

在 MATLAB Online 中打开

In your second function, you defined

k=1;

and the condition in the while loop is

while (p>k)

which is not fulfilled for any p>1. Then, neither index nor highestvalue get to be defined within the while loop and by extension, within the function.

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Answer 2

Harm 2014-10-15

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/158706-save-answers-for-different-values-used-in-a-while-loop-in-an-array-of-2-n#answer_155243

在 MATLAB Online 中打开

thanks David,

A little additional question:

I get the (2,d) array, the only thing what now is left is that the right values should get on the right position in the array.

I filled in d=4. I get only values in the last column. How can i adjust my code to get values in every column?

>> opgave30c2(4)

ans =

     0     0     0     1
     0     0     0     2

Thanks

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David Sanchez 2014-10-15

在 MATLAB Online 中打开

Initialize outside the for loop:

    iter=1;
    pnew=[];
for plocation=1:d
    k=1;
    p=plocation;
    r=rem(p,2);
    amountofsteps=1;
    answerarray=zeros(2,d);
    while (p>k)
        if (r==0)
            pnew(iter)=p/2;
        elseif (r>0) 
            pnew(iter)=p*3+1;
        end
...