convert from Matlab to equation (formula)

Hello, I hope you are doing well

Just a simple question, I have this short code which includes a loop:

syms Y3 GOD

for j=1:numel(Y3)     
      if j==1              
          GOD(j)=Y3(j);
      else
          GOD(j)=Y3(j)-sum(GOD);                
      end          
 end

I am very intuitive with matlab, and I am not so good in algebra, how can I write these lines of code as formula?

I know there are several ways to convert a formula to matlab code but not the other way around....

any suggestion is higly appreciated

Best

[David Hill]

What are Y3 and GOD initially? You define as sybolic, but treat as an array.

[Jules Ray]

thank for your question, GOD is the output, Y3 is just a vector of 5 elements e.g. Y3=[1 2 3 4 5];

Best

Answer 1

[Walter Roberson]

syms Y3 [1 5]
syms GOD [1 5]
for j=1:numel(Y3)     
      if j==1              
          GOD(j)=Y3(j);
      else
          GOD(j)=Y3(j)-sum(GOD(1:j-1));                
      end          
end

GOD.'

ans = 

GOD2 = [Y3(1), Y3(2:end)-Y3(1:end-1)];
GOD2.'

ans = 

So you can replace the loop with the formula I show in GOD2

[Jules Ray]

wonderful

thank you very much