'inline' command at 'for' loop... can we?

can we put 'inline' command at 'for' loop

I want to save several inline function at an array... Available?

Answer 1

[Friedrich]

Hi,

yes it should be possible but its better to create some Anonymous Functions instead of using inline, e.g.

f = cell(10,1);
for i=1:10
    f{i} = @(x) x*i;
end

The output of f looks a bit strange because it seems to be the same function handle all the time, but it isn't:

>> f{1}(1)

ans =

       1

>> f{2}(1)

ans =

       2

>> f{3}(1)

ans =

       3

>> f{3}(4)

ans =

      12

Or:

f = cell(2,1);
for i=1:2
    tmp = inputdlg('enter function handle')
    f{i} = eval(tmp{:})
end

And enter things like:

   @(x)x^2
   @(x)x-3

Make the call to eval fail proof!!

[Daniel Shub]

There is no need to hit it with the evil eval hammer, str2func seem perfectly designed for this purpose with hopefully a lot less side effects

Answer 2

[Masoud Ghanbari]

Hi

Actually I want to get the function from user and save it

not to be defined as f{i} = @(x) x*i;

[Jan]

Please do not post details of the question as an answer, but inster it in the question, where readers expect them.

What does "get the function from user" exactly mean? It is impossible to guess this reliably.

[Friedrich]

I think what he wants to do is the same as discussed here:

http://www.mathworks.com/matlabcentral/answers/71825-friday-fun-with-eval

Still dont use inline, use eval to generate the function handle. See me updated first post.

[Masoud Ghanbari]

Thanks Dear Friedrich

and what if i want to get the function from user by 2 variables like

f(i) = @(x,y) x+y

[Friedrich]

As long the user enters a valid matlab expression you are fine to eval it.

>> user_input = '@(x,y) x+y'

user_input =

@(x,y) x+y

>> my_fcn = eval(user_input)

my_fcn = 

      @(x,y)x+y

>> my_fcn(3,10)

ans =

      13

>>

[Masoud Ghanbari]

Why we got error while changing 'inputdlg' to 'input' below ???

f = cell(2,1);
for i=1:2
    tmp = inputdlg('enter function handle')
    f{i} = eval(tmp{:})
end

And why error when user inputs '@(x,y)x+y' at inputdlg

number=input(' How Many Conditions Do You Have ? ');
f = cell(number,1);
for i=1:number
    user_input = inputdlg('Enter The function :');
   f{i} = eval(user_input);
end

[Friedrich]

input returns a character array wheras inputdialog gives back a cell.

This @(x,y)x+y should give any error. What error do you get?

[Masoud Ghanbari]

When I Run

number=input(' How Many Conditions Do You Have ? ');
f = cell(number,1);
for i=1:number
    user_input = inputdlg('Enter The function :');
   f{i} = eval(user_input);
end

inputdlg appear and when i enter

@(x,y)x+y

i will face error at this line below

f{i} = eval(user_input);

[Iman Ansari]

Hi. Use this:

f{i} = eval(user_input{1});

[Masoud Ghanbari]

Hi Iman

It Does not work...

[Friedrich]

Dude ;) Post your intput and the error message. A simply does not work wont help.

[Masoud Ghanbari]

Ok Dear Friedrich ... Please Just Do What Ever You Know... I'm Really Stucked At This

See Here:

https://www.youtube.com/watch?v=zQiAgVLXknI

[Friedrich]

You need to zuse {} instead of () when you call eval. inputdlg gives back a cell. Also don't use i to index into it. This should work:

f{i} = eval(user_input{1})

Answer 3

[Masoud Ghanbari]

Ok Dear Friedrich ... Please Just Do What Ever You Know... I'm Really Stucked At This

See Here:

https://www.youtube.com/watch?v=zQiAgVLXknI