Undefined function or variable "Horz_average_l"

I read many answers for question: Undefined function or variable in forum, and check with my code, but i have not repaired that error. Can u see to help me?

function[Horz_average_l,Horz_average_r]= Horz_avg(Start,End,side) Sum =0; ITERATIONS = 200;

syms i j side Start End

switch side case 1

    for j=0: (ITERATIONS-1),
        for i=Start(j): (Start(j)+End(j))/2-1
            Sum = Sum + BWPic(i,j); 
        end
        Horz_average_l(j)= Sum/((End(j) - Start(j))/2); %Left side only */ 
        Sum = 0; 
    end
case 2

    for j=0:(ITERATIONS-1) 
        for i=((Start(j)+End(j))/2) : (End(j)-1)
        i = i +1;
        Sum = Sum + BWPic(i,j); 
        end 
        Horz_average_r(j)= Sum/((End(j) - Start(j))/2); % Right side only
        Sum = 0; 
    end
end
for j = 0 : (ITERATIONS-4)
    if  Horz_average_l(j+1) >=Horz_average_l(j) && Horz_average_l(j+2) < Horz_average_l(j+1) && Horz_average_l(j+3) >= Horz_average_l(j+2)
end
end

error in the last if

Undefined function or variable "Horz_average_l".

Answer 1

[Thorsten]

The last if seems to have no body.

Please format all your code.

Why do you use

syms i j side Start End

Where is PWPic defined?

And what is the function exactly supposed to do?

[Tan Phan]

Thanks for ur answer

1. if i dont use

 syms i j side Start End

i make a error :Not enough input arguments.

2. PWPic is a matrix 100x100 with value 0 and 1 that i defined in another m.file.

Thanks!

[Thorsten]

I still do not understand why you need to use symbolic variables i j side Start End

How are Start and End defined?

What is the function supposed to do?

You have defined Start and End as arguments of your function. So you have to pass them when you call the function. Otherwise you get the "Not enough input arguments."

So you should have defined Start and End outside your function and then call is like

mystart = ... % whatever your variable is defined
myend = ...

[hl hr] = Horz_avg(mystart,myend,1);

[Tan Phan]

Thanks Mr Thorsten!

I try your way and it is better. really do not need

syms i j side Start End

I declare my variables in global and it is recognized!