bugGNU Octave - Bugs: bug #34852, incorrect column number on error...


bug #34852: incorrect column number on error messages

Submitted by:  None
Submitted on:  Thu 17 Nov 2011 08:21:19 PM UTC  
Category:  Interpreter Severity:  2 - Minor
Priority:  3 - Low Item Group:  Incorrect Result
Status:  Confirmed Assigned to:  None
Originator Name:  delinquentme Originator Email:  -email is unavailable-
Open/Closed:  Open Release:  dev
Operating System:  Any

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Wed 01 Aug 2018 07:49:52 PM UTC, comment #9:

All good now with the list of operators in the Octave manual.

Rik <rik5>
Project Administrator
Wed 01 Aug 2018 07:33:45 PM UTC, comment #8:

Here's one more:


John W. Eaton <jwe>
Project Administrator
Wed 01 Aug 2018 06:59:39 PM UTC, comment #7:

Hey, that's an improvement. For the first case the column is reported as 31 as it should be. I still get a difference when the transpose operator is used, but maybe because that also looks like a quote character and there is another place in the code to accomadate that. If I eliminate the transpose then the column is correct again.

Rik <rik5>
Project Administrator
Wed 01 Aug 2018 02:53:08 AM UTC, comment #6:

I pushed the following changeset:


I don't know that it fixes everything, but it seems to improve the accuracy of the column numbers in the examples shown in comment #5.

With the new evaluator, it might be fairly easy now to generate better column numbers for stack traces as well, but that's a larger project.

John W. Eaton <jwe>
Project Administrator
Wed 01 Aug 2018 12:02:25 AM UTC, comment #5:

Marking as low priority. It seems better to print the column number because often it will be correct and help localize debugging. Occasionally, as in this instance, it can be off.

Another thing that could be improved, however, is getting the column numbers to add when there is more than one statement on a line. For example,

That's correct as 'z' appears in column 7. Now,

which is also correct. But as soon as you throw in operators things get off. In the following, z is at column 31 always but the the column is off in different ways.

Rik <rik5>
Project Administrator
Sat 19 Nov 2016 07:32:42 PM UTC, comment #4:

This issue is still present in Octave 4.2.0.

Here is the code of the original submission in runable form:

The resulting error message is

If I understand jwe's comment #2 correct, then it would be better if Octave did not mention any column number at all in this error message, since this column number is not adding any useful information anyways.

My personal opinion: There might as well be cases where the given column number makes debugging easier than without this column number. Just imagine code that has several commands on a single text line, like this

Hartmut <hardy>
Sat 27 Dec 2014 05:22:04 PM UTC, comment #3:

Added bug #43249 as a related bug. In that case, the reported line number from an error is incorrect rather than the reported column number.

Rik <rik5>
Project Administrator
Thu 17 Nov 2011 08:40:00 PM UTC, comment #2:

It's difficult to see here because the web interface eats whitespace (use verbatim ... verbatim tags here next time to enclose code), but the problem is that the error line is pointing to the assignment operator instead of the multiplication operator.

A relevant discussion from #octave follows:

Jordi GutiƩrrez Hermoso <jordigh>
Project Administrator
Thu 17 Nov 2011 08:36:46 PM UTC, comment #1:
Jordi GutiƩrrez Hermoso <jordigh>
Project Administrator
Thu 17 Nov 2011 08:21:19 PM UTC, original submission:

function [theta, J_history] = gradientDescent(X, y, theta, alpha, num_iters)

m = length(y); % number of training examples
J_history = zeros(num_iters, 1);

for iter = 1:num_iters

theta = theta - alpha/m * sum ( (((X*theta) - y) )*X )

J_history(iter) = computeCost(X, y, theta);




above code nets this error ( with an incorrect column number )


error: operator *: nonconformant arguments (op1 is 97x1, op2 is 97x2)
error: evaluating argument list element number 1
error: evaluating argument list element number 1
error: called from:
error: /home/thrive/Desktop/studies/machine_learning/ex1/mlclass-ex1/gradientDescent.m at line 9, column 11



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  • -email is unavailable- added by jwe (Posted a comment)
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    Follow 8 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2018-08-01 rik5 Priority5 - Normal => 3 - Low
    2014-12-27 rik5 Dependencies- => bugs #43249 is dependent
    2014-01-19 mtmiller CategoryNone => Interpreter
        Item GroupNone => Incorrect Result
        Release3.2.3 => dev
        Operating SystemGNU/Linux => Any
    2011-11-17 jordigh Severity3 - Normal => 2 - Minor
        StatusNone => Confirmed

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