Need to find Palindromic number with multipliers that are both n digits long.

Question

DJ V 2016-12-11

0
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https://ww2.mathworks.cn/matlabcentral/answers/316419-need-to-find-palindromic-number-with-multipliers-that-are-both-n-digits-long

评论： DJ V 2016-12-13

Okay, I seek palindromic number with multipliers that are both "n" digits long. Once I find a palindromic candidate, I must determine if it has multiples of "n" digits. For 100, I first locate 99, then I search for the multiples. Once it hits 9 the multiple is ll, and given that the "n" digit limit is 1 for this case, 9 and 11 won't work, because they aren't both "n" digits long. Once I start hitting combinations like 9 and 11, using a smaller integer than 9 as the multiple makes no sense, because they will always be larger than 11, which means they will never be n=1 long. At this point I need to start looking for a smaller palindrome, so I start the function over again using "q-1", which is one less than the previous palindrome candidate. I don't know how to stop the program, which I need to do at the bottom. How does one simply stop Matlab programatically?

function n = palin_product( dig,lim )
    if isnumeric(dig)== false
        n = 0;
        return;
    end
    if isnumeric(lim)==false
        n = 0;
        return;
    end
    c = floor(dig);
    multiplier1=10^c;
    multiplier1 = multiplier1-1;
    L=num2str(lim-1);
    n = lim-1;
    len = length(L);
    if mod(L,2)==0
        nucount=L/2;
    else
        nucount =floor(L/2);
    end
    q = lim-1
    for q =q:-1:1
        consider= q;
        L = num2str(q);
        if ceil(length(L)/2)-floor(length(L)/2)==0
            nucount= length(L)/2;
        else
            nucount= floor(length(L)/2);
        end
        for count = 1:nucount
            if L(count)==L(length(L)-(count-1))
                palin=true;
            else
                palin =false;
                break;
            end
            if palin ==true && count==nucount
                n = q;
                break
            end
        end
        if palin==true
            break;
        end
    end  
      for counter = (10^dig)-1:-1:10^(dig-1)
          if mod(q,counter)==0
              test = q/counter;
              if test >10^(dig-1)
                  q = q-1;
                  break;
              end
              n = q;
              break;
          else
              n =0;
          end
      end
      if length(num2str(q))<dig
          stop;
      end
      n = palin_product(dig,q);
  end