function handle does not work

Hello,

I started to work with function handles. But now I need some help to fix the problem in order to run the following code:

%Test for fhandle

for iTest = 1:3

%Create m-function

functionName = ['fHandleTest_',num2str(iTest),'.m'];
[fid,message] = fopen(functionName,'w');
fprintf(fid, 'function Output = Test(x)\n');
fprintf(fid, 'Output = x; \n');
fclose(fid);

%Execute function

fhandle = str2func(functionName(1:end-2));
out = fhandle(iTest)

end;

The following error occurs when I was running that code:

Undefined function 'fHandleTest_1' for input arguments of type 'double'.

Error in fHandleTest (line 14)
out = fhandle(iTest)

Besgt regards Stefan

Answer 1

[Jan]

The dynamic creation of M-files is not trivial, because MATLAB does not parse the folders during execution automatically. So you have to triggfer this time-consuming procedure manually:

% Test for fhandle
for iTest = 1:3
  %Create m-function
  functionName = ['fHandleTest_', num2str(iTest), '.m'];
  [fid,message] = fopen(functionName,'w');
  fprintf(fid, 'function Output = Test(x)\n');
  fprintf(fid, 'Output = x; \n');
  fclose(fid);

    %Execute function
    fhandle = str2func(functionName(1:end-2));
    rehash;   % <== 
    % Faster alternative:
    % clear(functionName(1:end-2))
    out = fhandle(iTest)
  end

Answer 2

[Bjorn Gustavsson]

For clarity and reduced confusion I suggest that you also name the funtion with the same name as the file. That is change:

fprintf(fid, 'function Output = Test(x)\n');

to:

fprintf(fid, 'function Output = fHandleTest_', num2str(iTest),'(x)\n');

Whenever I've taken shortcuts like that I've been bitten by it later.