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## newbie question: assigment to N-d arrays returns strange values

 From: John W. Eaton Subject: newbie question: assigment to N-d arrays returns strange values Date: Thu, 27 Oct 2005 13:56:08 -0400

```On  6-Aug-2005, Amir Seginer wrote:

| Hello,
|
| This might be a known problem, but I couldn't find any reference to it.
| When assigning to an n-dimensional array (see below) I get results which
| are different from Matlab. Also, in one case I get some strange values
| in the array as well.
|
| I wrote the the following code in Octave (using --traditional):
|
|  >>  m=zeros(3, 2, 2) ;
|  >>  a= [1 2 3 4] ;
|  >> m(3, :) = a
| m =
|
| ans(:,:,1) =
|
|          0        0
|          0        0
|          1        2
|
| ans(:,:,2) =
|
|          0        0
|          0        0
|          0        0
|
| which is not what I expected (3 and 4 were not assigned). Even worse,
| when I did
|
|  >> m=zeros(3, 2, 2) ;
|  >> a= [ 1; 2; 3; 4] ;
|  >> m(3, :) = a
| m =
|
| ans(:,:,1) =
|
|          0        0
|          0        0
|          1        2
|
| ans(:,:,2) =
|
|    0.0e+00  *
|
|        NaN      NaN
|        NaN      Inf
|        NaN      Inf
|
| This gives strange values on the 2nd "page". Further more, in normal
| mode the same code gave
|
| octave:8> m=zeros(3, 2, 2) ;
| octave:9> a= [ 1; 2; 3; 4] ;
| octave:10> m(3, :) = a
| m =
|
| ans(:,:,1) =
|
|    0  0
|    0  0
|    1  2
|
| ans(:,:,2) =
|
|      0.0000e+00   5.1715e-319
|     1.1116e-321    0.0000e+00
|      0.0000e+00    0.0000e+00
|
| Is there a way to overcome this, or at least get an error/warning. I'm
| using octave-2.1.71

Please try the following patch.

Thanks,

jwe

liboctave/ChangeLog:

2005-10-27  John W. Eaton  <address@hidden>

* Array.cc (assignN): Reshape to final size instead of resizing.

Index: liboctave/Array.cc
===================================================================
RCS file: /usr/local/cvsroot/octave/liboctave/Array.cc,v
retrieving revision 1.124.2.8
diff -u -r1.124.2.8 Array.cc
--- liboctave/Array.cc  2 Jun 2005 18:39:53 -0000       1.124.2.8
+++ liboctave/Array.cc  27 Oct 2005 17:52:30 -0000
@@ -3156,7 +3156,7 @@
}

if (retval != 0)
-       lhs.resize (final_lhs_dims);
+       lhs = lhs.reshape (final_lhs_dims);
}

if (retval != 0)

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```

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