function handle
in [Matlab]
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From: Stefan on 1 Apr 2010 08:58 Hello, Can someone help me on this ? Suppose I have the following function defined in an m-file. ============= function grad=testfn(x) grad=[]; %grad = x end ============= The I type the following in command line. checkfn(@testfn) In checkfn, I want to test whether grad=[]. "isempty(grad)" doesn't seem to work. Can someone fix it for me please? Thanks ======== function g = checkfn(grad) if isempty(grad) %do this else %do that end end =======
From: Tim Love on 1 Apr 2010 09:13 "Stefan " <akinsakin(a)yahoo.com> writes: >Hello, >Can someone help me on this ? I can't properly answer your question. However, note that foo=(a)testfn checkfn(foo(5)) checkfn(foo) will run your "do this" code then your "do that" code.
From: Jan Simon on 1 Apr 2010 09:47 Dear Stefan! > In checkfn, I want to test whether grad=[]. "isempty(grad)" doesn't seem to work. "Doesn't seem to work" is not really precise. Did you get an error message? In most cases the error message tells how to fix the problem already. If not, post it with the correspodning line of code. Kind regards, Jan
From: Steven Lord on 1 Apr 2010 09:48 "Stefan " <akinsakin(a)yahoo.com> wrote in message news:hp24vh$ar5$1(a)fred.mathworks.com... > Hello, > Can someone help me on this ? > > Suppose I have the following function defined in an m-file. > ============= > function grad=testfn(x) > > grad=[]; > %grad = x > end > ============= > > > The I type the following in command line. > checkfn(@testfn) > > In checkfn, I want to test whether grad=[]. "isempty(grad)" doesn't seem > to work. Can someone fix it for me please? Thanks The code is working correctly. The function handle @testfn is not empty. If you want to check if the _output_ from the function when you execute it is empty, then you need to actually invoke the function handle. function g = checkfn(grad) % since you've defined grad to take an input % you need to call it with some input value. % I chose [] as an arbitrary value output = grad([]); if isempty(output) disp('The function you passed in returned an empty value.'); else disp('The function you passed in did NOT return an empty value.'); end g = output; % etc -- Steve Lord slord(a)mathworks.com comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ
From: Stefan on 1 Apr 2010 11:21 "Steven Lord" <slord(a)mathworks.com> wrote in message <hp286u$5vp$1(a)fred.mathworks.com>... > > "Stefan " <akinsakin(a)yahoo.com> wrote in message > news:hp24vh$ar5$1(a)fred.mathworks.com... > > Hello, > > Can someone help me on this ? > > > > Suppose I have the following function defined in an m-file. > > ============= > > function grad=testfn(x) > > > > grad=[]; > > %grad = x > > end > > ============= > > > > > > The I type the following in command line. > > checkfn(@testfn) > > > > In checkfn, I want to test whether grad=[]. "isempty(grad)" doesn't seem > > to work. Can someone fix it for me please? Thanks > > The code is working correctly. The function handle @testfn is not empty. > If you want to check if the _output_ from the function when you execute it > is empty, then you need to actually invoke the function handle. > > > function g = checkfn(grad) > > % since you've defined grad to take an input > % you need to call it with some input value. > % I chose [] as an arbitrary value > output = grad([]); > if isempty(output) > disp('The function you passed in returned an empty value.'); > else > disp('The function you passed in did NOT return an empty value.'); > end > g = output; > % etc > > > -- > Steve Lord > slord(a)mathworks.com > comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ > Thank you Steve. That's exactly what I needed.
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