How can I call a value in side the a function which is already evaluated.

%% knt i calculated here.
nf=max(elem(:,4));
maxfl=max(elf(:,1));
for flno = 1:1:maxfl
   for i=elf(1,1)
       for j=1:1:nf
           p=CGx(j)-CGx(i); 
           au=[1,0,0;0,1,p;0,0,1];
           bu=(au)';
           kse=eval(['KSE',num2str(flno),'l']);
           k1=kse(1:nodof,1:nodof);
           eval(['Ktts',num2str(flno),'l','=[k1,-k1*au;-bu*k1,bu*k1*au]']); %Transformed Stiffness matrix of each floor (6x6)
       end
   end
end
%% I have to call the knt inside the loop, how can i call please suggest me.
function [t,k_hat, R, keyp, key,Keyp,Key, delu, k_T, delF_hat, deludot, u0, udot0, uddot0] = NewmarkNon( t,Ug, delF, dt, u_t, u_c,F1, KGf, C, MGf, Rt, Rc, R, gamma, beta, key, k_T,u,udot,uddot)
 knt=eval(['Ktts',num2str(n),'l']);  
end

[KSSV]

Give the necessary inputs of the function at the place you want to cal.....what is confusing you?

[Chaudhary P Patel]

for n=1:1:nf
    knt=eval(['Ktts',num2str(n),'l']);  
end

Sir, I want to use the knt inside the function.

Just tell me how can i call it in side the function.

[Chaudhary P Patel]

sir problem is that when i am calling the knt inside the loop it is telling that Ktts1l is undefined.

[Stephen23]

"problem is that when i am calling the knt inside the loop it is telling that Ktts1l is undefined."

What is KTTS1L supposed to be: a function, a script, a variable, an object ... ?

[Chaudhary P Patel]

knt=eval(['Ktts',num2str(n),'l']);

Ktts is elemental stiffness in which 1 means first element and l means local. calculated from the knt.

[Chaudhary P Patel]

@KSSV & @Stephen23 Sir, Please help me.

[Stephen23]

Please answer this question: what is KTTS1L supposed to be: a function, a script, a variable, an object ... ?

[Chaudhary P Patel]

eval(['Ktts',num2str(flno),'l','=[k1,-k1*au;-bu*k1,bu*k1*au]']);

Sir, Ktts is Variable which is storing the elemental stiffness in form of Ktts1l, Ktts2l,.......

[Rik]

Why are you generating variables, instead of using indexing?

[Chaudhary P Patel]

Sir, for another operation i have to use that value that's whay i am calling it inside the function.

Sir, it will be a great help if you could help me out from this problem.

[Stephen23]

"Ktts is elemental stiffness in which 1 means first element"

So (as KSSV correctly asks), why are you not using indexing?

"Sir, Ktts is Variable which is storing the elemental stiffness in form of Ktts1l, Ktts2l,......."

Please show how you do that.

[Chaudhary P Patel]

sir, in first loop i showed how am i calculating the all Ktts.

All these Ktts i am calling for all n=1:10 in second loop which is inside the Function loop.

Sir, for further operation inside the Function loop i need that, that's why i am calling.

Please you suggest me how can i call it.

[Stephen23]

"Please you suggest me how can i call it."

The best solution is to use indexing. Get rid of all of those ugly EVALs and use indexing into one array.

[Chaudhary P Patel]

Sir, i will do indexing later on but for this i want to complete it with same commands so please suugest if you could because it is large programme so it will take more time to change many things.

[Rik]

Since you will completely redesign your code to use indexing, isn't it more effective to first wait for you to rework you code? Perhaps some or most of your problems disappear or become trivial with the changes you make. You would be surprised how often that happens when people switch from eval to arrays...

[Chaudhary P Patel]

Sir, that is fine.

I did this function calling before this but this time i getting problem because of this Function loop.

Sir, any how please suggest me how can i call it, rest of things i will manage.

[Chaudhary P Patel]

@Walter Roberson @George Papazafeiropoulos sir, help me.

[George Papazafeiropoulos]

['Ktts',num2str(n),'l'] must be an input argument to the NewmarkNon function.

[Chaudhary P Patel]

Thank you @George Papazafeiropoulos Sir for your reply,

But how to write this in the input argument.

[Stephen23]

"But how to write this in the input argument."

Using exactly the same horrible, complex, inefficient approach you used to generate those variables: using EVAL.

[Chaudhary P Patel]

Sir, please tell me some way to proceed it with eval.

[Rik]

You have been told already what you should do: use arrays. Do you expect Stephen to give you advice about implementing a solution with eval? I know him as one of the most vocal opponents of the use of eval, so I don't expect that to happen.

[Chaudhary P Patel]

Sir, I just want a help from any person.

Sir,please help me if you can, it will be very helpful for me.

[Walter Roberson]

What you want to do cannot be done using eval. The variables assigned to in the script are not available inside the workspace of the function.

The main purpose of using functions is to encapsulate code and variables in a way that does not interfere with the calling code except through the defined interface layer, so if your function needs access to dynamic variables created by a different layer, then it is likely badly designed.

[Chaudhary P Patel]

sir, is there any way to proceed this operation without changing the code?

@George Papazafeiropoulos

@KSSV

@Rik

[Rik]

Let me try as well: No. There is no way to proceed this operation without changing the code.

You want help. We are giving you help, even if you don't like it. Asking again doesn't change the answer.

[Chaudhary P Patel]

Sir, it doesn't mean that I don't like your answer.

I'm sorry if you felt that way.

sir if i will change the code it will eat more of my time so i want to go ahead with your help without changing the code.

[Stephen23]

"is there any way to proceed this operation without changing the code?"

No.

[Chaudhary P Patel]

Thank you so much sir.

Answer 1

[Bruno Luong]

If you want to retrieve value of a variable from the parent workspace inside a function without passing it as argument onstead of normal eval do this

knt = evalin('caller','Ktts',num2str(n),'l'])

[Chaudhary P Patel]

@Bruno Luong Sir, how can i keep this in the input argument.

[Bruno Luong]

Use eval to call your function and put the ugly ['Ktts',num2str(n),'l'] somewhere in the argment list.

You'll soon end up with code having eval in every lines.

[Chaudhary P Patel]

Sir, if i am keeping ['Ktts',num2str(n),'l'] like this in the argument list it is showing error

"Invalid MATLAB Syntax"

[Chaudhary P Patel]

Sir, can i use "knt = evalin(['caller','Ktts',num2str(n),'l'])" directly without keeping it in the input argument.

[Bruno Luong]

Because you do it wrong I guess. You decide to use eval then then you commit yourself to debug te ugly code.

[Bruno Luong]

"Sir, can i use "knt = evalin(['caller','Ktts',num2str(n),'l'])" directly without keeping it in the input argument."

It's your code you do whatever you like? You ask me one way or another, I tell you the hint of doing both.

[Chaudhary P Patel]

ok sir.

Thank you so much.

[Walter Roberson]

Postponing fixing your code by locking in using a hack like this is just going to result in it taking even longer to fix your code later.

Answer 2

[Walter Roberson]

It is not possible to do what you want to do using eval(). You will need to rewrite your code.

[Walter Roberson]

Do not store variables like KSE3l -- use a cell array like KSEl{n} instead. Or possibly a multidimensional array.

Likewise do not store into Ktts*l -- use a cell array like Kttsl{n} instead.

%% knt i calculated here.
nf=max(elem(:,4));
maxfl=max(elf(:,1));
for flno = 1:1:maxfl
   for i=elf(1,1)
       for j=1:1:nf
           p=CGx(j)-CGx(i); 
           au=[1,0,0;0,1,p;0,0,1];
           bu=(au)';
           kse = KSEl{flno};
           k1 = kse(1:nodof,1:nodof);
           Kttsl{flno} = [k1,-k1*au;-bu*k1,bu*k1*au]']); %Transformed Stiffness matrix of each floor (6x6)
       end
   end
end

When you call your function (not shown in your code) pass in Kttsl as well.

%% I have to call the knt inside the loop, how can i call please suggest me.
function [t,k_hat, R, keyp, key,Keyp,Key, delu, k_T, delF_hat, deludot, u0, udot0, uddot0] = NewmarkNon( t,Ug, delF, dt, u_t, u_c,F1, KGf, C, MGf, Rt, Rc, R, gamma, beta, key, k_T, u, udot, uddot, Kttsl)
  n = something appropriate   
  knt = Kttsl{n};  
end

[Walter Roberson]

Please read http://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval for information about why we strongly recommend against creating variable names dynamically.