need to find numbers divisible by 2 through 100

hi i want to count the values in given vector/matrix that are divisible by 2-100.

y has few thousand random digits.

here is the code that i stitched but its giving me error. i want to create a vector divby which holds count of all values divisible by specific number and increment its corresponding value in value in the index .. say count of values divisible by 7 are held in divby(y) .. and after each iteration if a value is divisble by 7 divby[7] should increment by 1.

y=[3 3 43 45 2 2 34 5 ] % (it has a lot of such random values (most are 6 figure values) 

divby=[];
ndivby=[];

for k=2:99

      for i=1:length(y)
          if(mod(y(i),k)==0)
              divby(k)=divby(k)+1;
          else  
              ndivby(k)=ndivby(k)+1;

          end

      end
  end

i am getting below error Index exceeds matrix dimensions.

Error in all25k3rd (line 60) divby(k)=divby(k)+1;

Please help

Answer 1

[the cyclist]

Preallocate your arrays like this instead of as empty arrays:

divby=zeros(1,99);
ndivby=zeros(1,99);

Answer 2

[Azzi Abdelmalek]

There is a problem with your initialization, it should be zero instead of empty variable.

divby=[];
ndivby=[];

And also look at this part of your code

if(mod(y(i),k)==0)
        divby(k)=divby(k)+1;
    else  
        ndivby(k)=ndivby(k)+1;
    end

[Chamjiee Tramadol]

i hope it is achieving what i want . to see if there is a value other then 0 then either decrement or increment.

new to matlab dont will find a way t get c style increments to work. also code is not optimized thats for sure but ok

Answer 3

[Chamjiee Tramadol]

modified code as below

divby=zeros(1,99);
ndivby=zeros(1,99);

for k=2:99

      for i=1:length(y)
          if(mod(y(i),k)==0)
              divby(k)= divby(k)+1;
          else  
              ndivby(k)= ndivby(k)+1;

          end

      end
  end

while the error has gone. but i am not getting desired results..

var divby contains a lot of strange values. Columns 97 through 99

         279         321         279

Answer 4

[Chamjiee Tramadol]

thanks Azizi and cyclist both for your prompt responses. it resolved my issue.