I want to write a recursive Function that can calculate the sum of all the digit. If the input is 12345 then the answer will be 1+2+3+4+5 , without using string2num and loop.

function output= digit_sum(n)
if n<10
    output=fix(n);
end
if n>0
output=output+digit_sum(n*0.1);
end
end

I wrote this code but the problem I am facing is if i set output=0; anywhere then in all the recalling function process my result will turn to be 0, How to Solve this ?

[Stephen Cobeldick]

When n>=10 then you do not define output before that line, so when you refer to

... output + ...

MATLAB has no idea what output should be, because you have not defined it.

You need to consider your logic so that output is defined for all values before you try to use it.

[Asif Ahmed]

function output= digit_sum(n)
output=0;
if n<10
    output=fix(n);
end
if n>0
output=digit_sum(n*0.1);
end
end

If I set output=0 anywhere then the result is coming 0 .

[James Tursa]

Maybe you should take a step back and write down the algorithm on paper using words instead of code. Then take a simple 2 digit example and run it through your algorithm on paper. Once you have things figured out for your algorithm, then turn it into code and start testing. That will force you to understand the algorithm first, before you even get to the coding stage.

[Asif Ahmed]

Thanks for your help

Answer 1

[David Hill]

function output= digit_sum(n,a)
if nargin==1
    a=0;
end
if n<10
    output=a+fix(n);
else
    output=digit_sum(floor(n*.1),a+mod(n,10));
end

end

[Asif Ahmed]

There is just one input number digit_sum(n) .I just tried this but the output says 'Unrecognized FUnction or variable 'output'' Where i am mistaking ?

function output= digit_sum(n)
if n>0
output= (n/10 -fix(n/10))*10+digit_sum(fix(n*0.1));
end
end

[David Hill]

Using nargin, your function can have 1 or more inputs.

output = digit_sum(12345);

Try the above on my function.

[Asif Ahmed]

function output= digit_sum(n)

if n<10
    output=fix(n);
end
if n>0
output=((n/10 -fix(n/10))*10)+digit_sum(fix(n*0.1));
end
end

Thanks , I got the problem where i was mistaking,Now the code runs fine. Thanks for your help.

function output= digit_sum(n)

if n<10
    output=fix(n);
end
if n>0
output=mod(n,10)+digit_sum(fix(n*0.1));
end
end

Answer 2

[Saptarshi Neogi]

You can do this with any inbuit functions.

function x = digit_sum(n)
x=0;
if n>0
    x=mod(n,10)+digit_sum(floor(n./10));%recursive
end

Answer 3

[Sanjay Raju]

function x=digit_sum(inp)
    if inp<10
        x=inp;
    else
        x = mod(inp,10) + digit_sum(fix(inp/10));
    end
end

Answer 4

[Farhath Surayya]

function output= digit_sum(n) if n<10 output=fix(n); end if n>0 output=output+digit_sum(n*0.1); end end