How to recall the answer of an if statement in matlab? - matlab

Question

I am writing a function, which is suppose to give the result of the following if statement:
s=some scalar
i=some scalar ;
if y(s,i)==L
U(1,i)==0
else disp('Never binding') ;
end
How can I store the "answer" so that the name given to the answer is the output of the function?
for example: ans=R and function R=myfunction(i,s)
Is this possible?
for example if i run my code:
if y(8,1)==L
U(1,1)==0
else disp('Never binding')
end
ans =
X1_2*a - P1_2*X1_2 - X1_2^2*b + X1_2*(LL*(g1_2 + g2_1) + LL*(g1_3 + g3_1)) == 0
or another case:
if y(1,1)==L
U(1,1)==0
else disp('Never binding')
end
Never binding
Here is the code for the complete function:
function R=myIR1(s, n , agent)
x = 'HL'; %// Set of possible types
K = n; %// Length of each permutation
%// Create all possible permutations (with repetition) of letters stored in x
C = cell(K, 1); %// Preallocate a cell array
[C{:}] = ndgrid(x); %// Create K grids of values
y = cellfun(#(x){x(:)}, C); %// Convert grids to column vectors
y = [y{:}];
e=size(y,1);
X = sym('X',[n e], 'positive' );
P = sym('P',[n e], 'positive' );
G=sym('g' , [n,n]) ;
syms c a b ;
s=s;
A = char( zeros(n,2*n) ) ;
for col=1:n
Acol = [col col+1] + (col-1) ;
A(:,Acol) = [ y(s,col)*ones(n,1) y(s,:).' ] ;
end
A1 = reshape( cellstr( reshape(A.',2,[]).' ) , n , n ).' ;
B=A1.*(G+G') ;
B(logical(eye(size(B)))) = 0 ;
for i=1:n
U(i)=[a*X(i,s) - b*(X(i,s))^2 + X(i,s)*(sum(B(:,i).*X(:,s))) - X(i,s)*P(i,s)];
end
agent=agent ;
syms H L ;
i=agent ;
if y(s,i)==L
U(1,i)==0
else disp('Never binding') ;
end
IR is not assigned to anything, I want to assign it to the answer of the if statement..
Thank you

Answer 1

Yes, just assign R to be whatever you want inside the function body. When the function terminates, whatever R was assigned to is the final output that gets sent back to the user.
For example:
function R = myfunction(i,s)
...
...
...
R = ... ;%// Assign the value of R you want here
...
...
end
Then in the MATLAB Command Prompt, you would do:
R = myfunction(i,s);
When calling this function, R will contain whatever you assigned it to be in the function itself. However, you need to make sure that R gets assigned to something before the function terminates. If you don't, then MATLAB will give you an error telling you that you forgot to assign R something as it's expected to be the output.
Given your code, it looks like the main assignment that you want to store is done in the if statement at the end of your code. You're actually not storing that assignment to a variable. In particular:
if y(s,i)==L
U(1,i)==0
else disp('Never binding') ;
end
If you don't assign a variable to something, it automatically gets stored in a variable called ans, which is what you're echoing to the command prompt as you're not placing a semi-colon in front of the U(1,i) == 0 statement. I believe you want to take this output and assign it to R as R is the final output variable you want, so just do this. Note that your output variable is called IR and not R so make sure you change the output variable to R in the function:
if y(s,i)==L
R = U(1,i) == 0;
else disp('Never binding') ;
end
Place a semi-colon at the end of the statement so it doesn't unnecessarily echo the output to the screen.