How to put a function definition into a string?

I have a script, and I have an in-line function definition, for example like this:

f = @(a,x) 1./(1+exp(-tan(a).*(x-a)));

I want to write this function out into a text file, or a string variable. So I need

mystring = '1./(1+exp(-tan(a).*(x-a)))'

or

'@(a,x) 1./(1+exp(-tan(a).*(x-a)))'

Answer 1

[Walter Roberson]

f = @(a,x) 1./(1+exp(-tan(a).*(x-a)));
mystring = char(f)

[Mr M.]

Thanks, and whatif I have the name of a function in a string like 'f', and I want to pass this name into char(), so I need char(f), but I have only mystring = 'f'?

[Walter Roberson]

Then you avoid doing that.

Two approaches:

1) Store all of the handles as fields of a struct. When you get the name such as 'f', use dynamic field names to pull out the content. For this to work, the identifiers must be valid MATLAB variable names:

appropriate_handle = MyStruct.(mystring)

2) Store all of the handles in a cell array, and have another cell array of their corresponding identifiers (which would not have to be valid MATLAB identifier names). When the user selects from one of the identifiers, locate it in the list of identifiers and use the corresponding position to access the content of the cell array:

which_one = input('Which function name do you want?', 's');
[tf, idx] = ismember(which_one, list_of_names);
if tf
   appropriate_handle = cell_of_handles{idx};
else
   error('That was not a name')
end

or

idx = get(handles.list_of_functions, 'value')
if isempty(idx)
   error('You must select an entry from the list')
end
appropriate_handle = cell_of_handles{idx};