Opened 14 years ago

Closed 14 years ago

# pmat abbreviates matrix entriew without notice

Reported by: Owned by: Simon King hannes minor Release 3-1-0 singular-libs

### Description

The following happens both with the CVS-version (February 16, 2009) and with Singular-Versions before 3-0-4:

```>    ring r=0,(x,y,z),ls;
>    ideal i= x,z+3y,x+y,z;
>    matrix m[3][3]=i^2;
>    pmat(m);
x2,     xz+3xy,     xy+x2,
xz,     z2+6yz+9y2, yz+3y2+xz+3xy,
z2+3yz, y2+2xy+x2,  yz+xz
>    pmat(m,5);
x2    xz+3x xy+x2
xz    z2+6y yz+3y
z2+3y y2+2x yz+xz
```

So, in `pmat(m,5)`, several matrix entries are abbreviated, but it is impossible to guess whether `yz+3y` is a valid polynomial or just an abbreviation of `yz+3y2+xz+3xy`.

Moreover, I find it not nice that `pmat(m)` uses ", " as column separator, whereas `pmat(m,5)` just uses " " (single blank space, no comma) as separator.

Therefore, after my suggestion, `pmat` was changed in Singular-3-0-4, so that the output was:

```   pmat(m);
x2,     xz+3xy,     xy+x2,
xz,     z2+6yz+9y2, yz+3y2+xz+3xy,
z2+3yz, y2+2xy+x2,  yz+xz
pmat(m,5);
x2,    xz+.., xy+x2,
xz,    z2+.., yz+..,
z2+.., y2+.., yz+xz
```

Hence, in Singular-3-0-4, the pmat-output clearly shows whether a matrix entry was abbreviated or not.

Is there a good reason why Singular-3-1-0 should return to the old confusing output of pmat? Otherwise I suggest to keep pmat as it is in Singular-3-0-4.

### comment:1 Changed 14 years ago by seelisch

Owner: changed from somebody to hannes

### comment:2 Changed 14 years ago by hannes

Resolution: → fixed new → closed

CVS: back to 1.30, with id->@@id change from cvs log

### comment:3 Changed 14 years ago by greuel@…

The changes of Simon in 3-0-4 should be included in 3-1-0. Gert-Martin

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