How to know if a string is a valid matlab function ?

Hi,

I'm looking for a function which can tell me if a string is a valid matlab function.

For exemple :

function_i_m_looking_for('sin'); % should return 1
function_i_m_looking_for('toto'); % should return 0

Thank you

Answer 1

[Mehmet OZC]

You can simply run the function below, hope it helps.

function output = function_i_m_looking_for(x)
output = 1;
try 
    type(x)
catch
    output = 0;
end
end

[per isakson]

To suppress the output to the screen, replace

    type(x)

by

    evalc( 'type( ''x'' )' );

Answer 2

[Walter Roberson]

regexp(x, '^[A-Za-z]\w*$') && ismember(exist(x), [2 3 5 6])

The beginning bit filters out embedded operators and file extensions and directory specifiers that exist() would otherwise pay attention to. 2 would be .m file on your search path, 3 is mex file on search path, 5 is built-in MATLAB function, 6 is .p file on search path. You might also want to include 8 which is class name.

[Star Strider]

Elegant!

[Walter Roberson]

Elegant is not what I would call it ;-)

[per isakson]

I call it smart, however ...

>> str = '+';
>> regexp( str, '^[A-Za-z]\w*$' )
ans =
     []
>> regexp( str, '^[A-Za-z]\w*$' ) && true
Operands to the || and && operators must be convertible to logical scalar values. 
>>

Why isn't there a regular expression function, which returns a logical value?

.

A modified one-liner

    >> not(isempty(regexp( str, '^[A-Za-z]\w*$' ))) && true
    ans =
         0

Answer 3

[Charly]

Thank you for your answers

[Jos (10584)]

This will also work for non-functions, like text files etc ...

Answer 4

[Jos (10584)]

FYI, I just upload my function ISFUNCTION to the File Exchange:

http://www.mathworks.nl/matlabcentral/fileexchange/45778-isfunction