I would like to do such thing :

[code]
PARAMS={'struct.x',[1 2 3]};

for i=1:length(PARAMS{2})
        assignin('base',PARAMS{1},PARAMS{2}(i));
end
[\code]

The user should input the name of the variable that would be changed into the loop as a first field in the PARAMS cell array.The different values of the variable are given into an array.  

But MatLab give me the following error: 
??? Error using ==> assignin
Invalid variable name "struct.x" in ASSIGNIN.

Apparently the assignin function cannot be used to assign values into struct fields. Is there another function or a better way to do such thing ?

Thanks in advance.

"Sébastien " <sebastien.grolleau.removethis@cea.fr> wrote in message 
news:hh4m8s$2lj$1@fred.mathworks.com...
>I would like to do such thing :
>
> [code]
> PARAMS={'struct.x',[1 2 3]};
>
> for i=1:length(PARAMS{2})
>        assignin('base',PARAMS{1},PARAMS{2}(i));
> end
> [\code]
>
> The user should input the name of the variable that would be changed into 
> the loop as a first field in the PARAMS cell array.The different values of 
> the variable are given into an array.
> But MatLab give me the following error: ??? Error using ==> assignin
> Invalid variable name "struct.x" in ASSIGNIN.
>
> Apparently the assignin function cannot be used to assign values into 
> struct fields.

That's correct.  The second input to the ASSIGNIN function must be a 
_variable name_, not an _expression_ like 'struct.x'.

> Is there another function or a better way to do such thing ?

Why are you trying to create a struct array in the base workspace from 
within your script or function?

My suggestion for "a better way to do such thing" is "find a way to avoid 
having to create such a variable", but that's just me.

If you _MUST_ do so, construct the structure inside your function and assign 
it into the struct array in the base workspace.

assignin('base', 'struct', struct('x', 1));

But two things:

1) This "poofs" a variable into the base workspace -- all the Bad Things 
that we've discussed on this newsgroup in the past with regards to poofing 
variables applies in this case.

2) Don't create a variable named struct in any workspace if you want to be 
able to use the STRUCT _function_ that creates a struct array -- use a 
different name.

-- 
Steve Lord
slord@mathworks.com
comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ 

"Sébastien " <sebastien.grolleau.removethis@cea.fr> wrote in message <hh4m8s$2lj$1@fred.mathworks.com>...
> I would like to do such thing :
> 
> [code]
> PARAMS={'struct.x',[1 2 3]};
> 
> for i=1:length(PARAMS{2})
>         assignin('base',PARAMS{1},PARAMS{2}(i));
> end
> [\code]
====================

Even if it were possible, the for-loop you've written here would seem to overwrite struct.x 3 times successively with different values. In other words, it would be equivalent to the one-liner

assignin('base',PARAMS{1},PARAMS{2}(end));


==========================
> The user should input the name of the variable that would be changed into the loop as a first field in the PARAMS cell array.The different values of the variable are given into an array.  
> 
> But MatLab give me the following error: 
> ??? Error using ==> assignin
> Invalid variable name "struct.x" in ASSIGNIN.
> 
> Apparently the assignin function cannot be used to assign values into struct fields. Is there another function or a better way to do such thing ?
===========================

Perhaps the setfield() command is what you're looking for?