Talk:Reduced row echelon form: Difference between revisions

== Still bug in java version? ==

I tried to run the the java code on matrix

<pre>

1, 2, 3, 4, 3, 1

2, 4, 6, 2, 6, 2

3, 6,18, 9, 9,-6

4, 8,12,10,12, 4

5,10,24,11,15,-4

</pre>

which correctly resulted in

<pre>

1, 2, 0, 0, 3, 4

0, 0, 1, 0, 0, -1

0, 0, 0, 1, 0, 0

0, 0, 0, 0, 0, 0

0, 0, 0, 0, 0, 0

</pre>

and then applied the code on this resulting matrix which generated an error. It seems that step 1 and step 2 do not recognize the correct pivot column for examples where there exist free variables in front of pivot columns (In the example above the second column of the resulting matrix). I corrected this by changing method isColumnZeroes not to consider the whole column:

<lang java>

public boolean isColumnZeroes(Coordinate coordinate) {

for (int i = coordinate.row; i < this.height; i++) { // <- not from i=0!!!!11

if (this.matrix[i][coordinate.col].getRatio() != 0.0) {

return false;

}

}

return true;

}

</lang>

Now it works. All the other examples are also solved correctly. I have to admit that I changed the code so I am not sure that this error also occurs in the original version.