Why this result?



Patrick Gelin wrote:
> Hi,
> 
> this is a small maxima session:
> 
> matrix(
>  [5,7], 
>  [5,x]
> );
> (%o3) matrix([5,7],[5,x])
> (%i4) echelon(%);
> (%o4) matrix([1,7/5],[0,1])
> 
> Why the result is [0,1] and not [0,x-7] ?
> 
echelon says the first non-zero element in each row is one.
I guess maxima assumed x-7 is never zero and divided it out to produce 1.

This looks like a bug.  At the very least, it should have asked if x-7 
is zero or not.

Ray