Re: Need test run in Matlab

[Andrew Janke]

On 1/31/19 3:05 PM, John W. Eaton wrote:
> On 1/29/19 2:39 PM, Christian Himpe wrote:
>> Here is the output of the corrected script.
> 
> Thanks.
> 
> I'm a bit confused by these results.  Maybe I'm missing something, but I
> don't understand the case of f3(1), which shows that "sigma -1" is
> evaluated as a command.  Compare this with f1(), which fails when there
> is a variable in the local workspace that conflicts with the name of the
> function (sigma).  How does that make sense?
> 
> Functions:
> 
> function f1 ()
>   sigma = svd (1);
>   eval ('sigma -1;');
> end
> 
> function f3 (sigma)
>   eval ('sigma -1;');
> end
> 
> function r = sigma (opt)
>   global sigma_call;
>   if (nargin == 0)
>     sigma_call = 'function';
>     r = 1;
>   elseif (ischar (opt))
>     sigma_call = 'command';
>     r = 1;
>   else
>     sigma_call = 'unexpected';
>   end
> end
> 
> Output you sent for calling f1() and f3(1):
> 
> f1: error: Error using f1 (line 3)
> Error: "sigma" was previously used as a variable, conflicting with its
> use here as the name of a function or command.
> See "How MATLAB Recognizes Command Syntax" in the MATLAB documentation
> for details.
> f1 (): none
> 
> f3 (1): command
> 
> Here are the functions:
> 
> function f1 ()
>   sigma = svd (1);
>   eval ('sigma -1;');
> end
> 
> function f3 (sigma)
>   eval ('sigma -1;');
> end
> 
> function r = sigma (opt)
>   global sigma_call;
>   if (nargin == 0)
>     sigma_call = 'function';
>     r = 1;
>   elseif (ischar (opt))
>     sigma_call = 'command';
>     r = 1;
>   else
>     sigma_call = 'unexpected';
>   end
> end
> 
> Why should f3(1) succeed in calling sigma as a command-style function
> when f1() fails with an error message about sigma defined as a variable
> and later being used as a command-style function?  Isn't sigma defined
> as a variable in both cases prior to the use as a function?
> 
> jwe
> 

I've got nothing. It's a surprise to me that f3(1) is not erroring. I
know that's not very helpful, but at least you're not overlooking
anything obvious as far as I can tell.

Cheers,
Andrew