Calculate a varibale matrix for a specific value

I know this is a beginnary question. But I couldn't find a solution for it.

syms x;
A(x)=[x,x+1,x-1];
A(2)

[Awais Saeed]

You did not explain what you are trying to acheive and what is the problem. A(2) gives you [2 3 1] though.

Answer 1

[Walter Roberson]

syms x;
A(x)=[x,x+1,x-1];
A(2)

ans = 

I suspect that you are trying to index the formula A(x) to extract the x+1 .

If so, then you cannot do that directly.

When you define a symbolic function like you do on the second line, then MATLAB starts with a sym() object and attaches subsref() behaviour for indexing with () indices. The subsref() behaviour that is attached to the symbolic function object is that () indexing works like

extract the variables from the defined parameter list

find the underlying sym() object representation,

subs() into that symbolic representation replacing the

parameter variables with the values that are pass in through the () notation

After that is done, you cannot index into the formula to extract parts of the formula, because the () behavior has been defined as evaluating the formula according to the parameters passed in. Thus A(2) is subs([x,x+1,x-1], {x}, {2}) giving [2 3 1] .

What you can do, though, is

  parts = formula(A)

parts = 

  parts(2)

ans = 

[Sa Moha]

Thanks

What about this one:

A=zeros(2);
for i=1:2
    A{i}=[i,i;i,i];
    
end

I want to save each matrix in loop as A{i} or A(i) or something like this.

[Sa Moha]

I found it myself:

A=zeros(2);
for i=1:2
    A(1:2,2*i-1:2*i)=[i,i;i,i];
    A
end

[Walter Roberson]

A = cell(2, 1);
for i=1:2
    A{i}=[i,i;i,i];  
end

A

A = 2×1 cell array
    {2×2 double}
    {2×2 double}

A{2}

ans = 2×2

2 2 2 2