How to initialize a variable to zero in userdefined matlab function, which should be executed only once then the values should change dynamically

function [ia_avr] = fcn(ia)

iasum = iasum+Ia; 

                if xxxx
                    ia_num=ia_num+1;
                    ia_avr=ia_avr_old;

                elseif xxxx
                    ia_num=ia_num+1;
                    ia_avr=iasum/ia_num;
                    ia_avr_old=ia_avr;
         
                else            
                    ia_avr=ia_avr_old;
                    iasum=0;
                    ia_num=0;
                end
end

In this I want to initialize iasum,ia_num,ia_avr_old to 0. After which the values should change.

Answer 1

[Ameer Hamza]

Such cases are handled using persistent variables.

function [ia_avr] = fcn(ia)
    persistent iasum ia_num ia_avr_old
    
    if isempty(iasum) % only runs once
        iasum = 0;
        ia_num = 0;
        ia_avr_old = 0;
    end
    
    iasum = iasum+Ia; 
    if xxxx
        ia_num=ia_num+1;
        ia_avr=ia_avr_old;
    elseif xxxx
        ia_num=ia_num+1;
        ia_avr=iasum/ia_num;
        ia_avr_old=ia_avr;

    else            
        ia_avr=ia_avr_old;
        iasum=0;
        ia_num=0;
    end
end