bugGNU Octave - Bugs: bug #54781, Matrix creation functions (eye,...


bug #54781: Matrix creation functions (eye, rand, zeros, ...) allow invalid non-integer dimensions

Submitted by:  Kai Torben Ohlhus <siko1056>
Submitted on:  Thu 04 Oct 2018 02:19:30 PM UTC  
Category:  Interpreter Severity:  4 - Important
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  Fixed Assigned to:  None
Originator Name:  Open/Closed:  Closed
Release:  dev Operating System:  Any

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( Jump to the original submission)

Fri 12 Oct 2018 08:12:15 AM UTC, comment #10: 

Awesome =)  In the spirit of your changes Rik, I added a small change for "eye()" in cset https://hg.savannah.gnu.org/hgweb/octave/rev/a533a7c4d2cc .

Regarding comment #8 for Matlab R2018b:

>> x = zeros ([2, 1.1, 2])
Error using zeros
Size inputs must be integers.

Same for Octave now (with your patches applied) =)

I really consider this item to be fixed/closed as well.  Thank you Rik and jwe for your help!

Kai Torben Ohlhus <siko1056>
Project Member
Thu 11 Oct 2018 10:49:33 PM UTC, comment #9: 

I pushed another changeset which fixes the remaining issue (https://hg.savannah.gnu.org/hgweb/octave/rev/d6581134daaa).  This revealed that Octave was doing an inappropriate conversion in rand() of a dimension vector in to an int type rather than an octave_idx_type.

Marking bug as fixed and closing report.

Rik <rik5>
Project Administrator
Thu 11 Oct 2018 09:13:02 PM UTC, comment #8: 

For compatibility, what does Matlab return for

x = zeros ([2, 1.1, 2])


Rik <rik5>
Project Administrator
Thu 11 Oct 2018 09:05:57 PM UTC, comment #7: 

I pushed a changeset that fixes all of the utility matrices like eye, ones, etc. as well as rand.  See https://hg.savannah.gnu.org/hgweb/octave/rev/373fe1608f7c.  I also added some BIST tests while I was at it. 

The remaining issue is a dimension vector such as

x = zeros ([2, 1.1, 2])

which still passes.

Rik <rik5>
Project Administrator
Thu 11 Oct 2018 07:14:17 PM UTC, comment #6: 

Rik, thanks for taking care of this.  I applied file #45170 and can confirm the outputs of comment #5.

It improves the situation for the creation matrices, except for "rand".  I think it should be applied to all four overloaded versions of libinterp/corefcn/data.cc (fill_matrix) and we leave this report open.

Kai Torben Ohlhus <siko1056>
Project Member
Tue 09 Oct 2018 05:38:14 PM UTC, comment #5: 

Attached is a quick diff that works for me.  The error message is different now, but maybe that is okay?


octave:1> x = zeros (2, {1}, 2)
error: octave_base_value::double_value (): wrong type argument 'cell'
error: octave_base_value::int64_value (): wrong type argument 'cell'
error: zeros: dimension arguments must be scalar integers


octave:2> x = zeros (2, 1.1, 2)
error: zeros: conversion of 1.1 to int64_t value failed

It doesn't mention that the dimension must be a scalar integer.  On the other hand, it identifies the argument that is in error far better.

The diff is trivial

diff -r 2d5f48a39b7e libinterp/corefcn/data.cc
--- a/libinterp/corefcn/data.cc Mon Oct 08 23:04:24 2018 +0200
+++ b/libinterp/corefcn/data.cc Tue Oct 09 10:33:09 2018 -0700
@@ -3931,8 +3931,12 @@ fill_matrix (const octave_value_list& ar
         dims.resize (nargin);

         for (int i = 0; i < nargin; i++)
-          dims(i) = (args(i).isempty ()
-                     ? 0 : args(i).xidx_type_value ("%s: dimension arguments must be scalar integers", fcn));
+          {
+            if (args(i).isempty ())
+              dims(i) = 0;
+            else
+              dims(i) = args(i).idx_type_value (true);
+          }

However, this still doesn't error out if a dimension vector is used.

octave:1> x = zeros ([2, 1.1, 2])
x =

ans(:,:,1) =


ans(:,:,2) =


That is a different codepath in the function fill_matrix in data.cc.

(file #45170)

Rik <rik5>
Project Administrator
Tue 09 Oct 2018 05:09:04 PM UTC, comment #4: 

Agreed.  This was done for Matlab compatibility, but I never liked it either because I prefer strict input validation.  Marking bug as confirmed.

Rik <rik5>
Project Administrator
Thu 04 Oct 2018 04:09:12 PM UTC, comment #3: 

OK, I'd be glad to require dimension arguments to be integers.  I never liked the rounding behavior anyway.  It was only done in Octave for compatibility, as far as I know.

John W. Eaton <jwe>
Project Administrator
Thu 04 Oct 2018 03:04:24 PM UTC, comment #2: 

Okay, my Matlab experience refers to a much shorter timespan ;-)

At least R2018a errors in all cases with a hint to use integer dimensions only.

Kai Torben Ohlhus <siko1056>
Project Member
Thu 04 Oct 2018 02:36:17 PM UTC, comment #1: 

Originally, Matlab rounded (I think) non-integer values passed as dimensions to functions like eye, ones, and zeros.  So Octave did the same for compatibility.  What does modern Matlab do?

John W. Eaton <jwe>
Project Administrator
Thu 04 Oct 2018 02:19:30 PM UTC, original submission:  

While fixing another bug, I received errors, because of potentially erroneous test cases (maybe copy&paste errors from "sprand")

A = rand (n-3, n, .5);

Additionally, Octave does not error on the following statements, and silently creates nonsense:

>> A = eye (0.5), size(A)
A = [](0x0)
ans =
   0   0

>> A = eye ([2, 0.5]), size(A)
A = [](2x0)
ans =
   2   0

>> A = eye (2, 0.5), size(A) # works!
error: eye: conversion of 0.5 to int64_t value failed

Similar for "zeros" and "ones" (only the first as example given below:

>> A = zeros (0.5), size(A)
A = [](0x0)
ans =
   0   0

>> A = zeros (2, 0.5), size(A)
A = [](2x0)
ans =
   2   0

>> A = zeros (2, 0.5, 4), size(A)
A = [](2x0x4)
ans =
   2   0   4

Kai Torben Ohlhus <siko1056>
Project Member


(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach Files:

Attached Files
file #45170:  intidx.diff added by rik5 (659B - text/x-patch)


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    Follow 6 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2018-10-11 rik5 StatusConfirmed => Fixed
        Open/ClosedOpen => Closed
    2018-10-11 rik5 StatusPatch Submitted => Confirmed
    2018-10-09 rik5 Attached File- => Added intidx.diff, #45170
        StatusConfirmed => Patch Submitted
    2018-10-09 rik5 StatusNone => Confirmed

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