how to write 2 summations

Hello

i have got a problem writing this summation on matlab as function where my inputs are p and m

Answer 1

[Nora Khaled]

p=3;
m=4;
n=randi(5,p,m)

%for loop:
ans1=0;
for i=1:1:p
    for j=1:1:m
        ans1=ans1+n(i,j);
    end
end
ans1

%sum function
ans2=sum(sum(n))

Answer 2

[KSSV]

thesum = 0 ; 
for i = 1:p
    for j = 1:m
        thesum = thesum+n(i,j) ; 
    end
end