bugGNU Octave - Bugs: bug #58411, cellfun with...

 
 

bug #58411: cellfun with "ErrorHandler" returns wrong message

Submitted by:  Muhali <muhali>
Submitted on:  Wed 20 May 2020 12:28:54 PM UTC  
 
Category:  Octave Function Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Regression
Status:  Confirmed Assigned to:  None
Originator Name:  Open/Closed:  Open
Release:  6.0.90 Operating System:  GNU/Linux

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Mon 01 Jun 2020 10:36:56 PM UTC, comment #2: 

This bug has two parts.  The fact that the last value has nonsense in it, rather than NaN, is due to the "ErrorHandler" routine itself.  The function "foo" cycles over the range 1:nargout.  However, when the calling form is

cellfun (...)

nargout is equal to 0 so no value is assigned by the ErrorHandler.  This is why the invocation

x = cellfun (...)

works because nargout is equal to 1 in this case and the for loop works correctly.

However, what should happen, according to Matlab, is that an error gets thrown because the function is supposed to supply a value.  Matlab emits an error that says that "UniformOutput" is true (default) but the function failed to produce a value for index 3.

By setting "UniformOutput" to false, both Matlab and Octave produce the correct result

cellfun (@factorial, {1,2,-3}, "ErrorHandler", @cellfoo, 'uniformoutput', false)

Rik <rik5>
Project Administrator
Wed 20 May 2020 03:34:14 PM UTC, comment #1: 

Confirmed.  This is a regression from 5.2.  The behavior is the same on the development branch as well.

The second part is interesting.  To be clear, the output value is incorrect when assigned to the default variable ("ans").  But is correct if there is an actual assignment to a variable.

Rik <rik5>
Project Administrator
Wed 20 May 2020 12:28:54 PM UTC, original submission:  

in continuation of bug #58280: the code

function varargout = foo (S, varargin)
   S.message
   for i = 1 : nargout
      varargout{i} = NaN ;
   endfor
endfunction
cellfun ("factorial", {1,2,-3}, "ErrorHandler", @foo)

returns with ovtave-5

ans = factorial: all N must be real non-negative integers
ans =

    1.0000e+00    2.0000e+00   2.5233e-310

whereas octave-6 returns

ans =
ans =

    1.0000e+00    2.0000e+00   2.5233e-310

so the message is gone.

Moreover, the output of cellfun is only correct if I execute

fac = cellfun ("factorial", {1,2,-3}, "ErrorHandler", @foo)

which returns

fac =

     1     2   NaN

Muhali <muhali>

 

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    Follow 3 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2020-05-20 rik5 CategoryNone => Octave Function
        Item GroupNone => Regression
        StatusNone => Confirmed

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