A non-zero row
is a row that has at least one entry that is not zero.
The leading entry
of a row is the leftmost non-zero entry in a non-zero row.
A rectangular matrix is in echelon form
if it has the three properties:
1. All non-zero rows are above any rows of all zeros.
2. Each leading entry of a row is in a column to right of the leading entry of the row above it.
3. All entries in a column below a leading entry are zeros.
If the rectangular matrix satisfies 2 more additional properties, then it is in reduced echelon form
4. The leading entry in each non-zero row is 1.
5. Each leading 1 is the only non-zero entry in its column.
Essentially the difference between the two forms is that the reduced echelon form has 1 as a leading entry, and the column of the leading entry has 0’s below and above.
The pivot position
is just the leading entries
of the echelon form matrix.
The pivot column
is the column of the pivot position.
Here are the steps for the row reduction algorithm
1. Look for the leftmost non-zero column. This is our pivot column.
2. Find a non-zero entry in the pivot column. This is our pivot position. It should be at the very top of the pivot column.
3. Use matrix row operations to make all the entries below the pivot 0
4. Ignore the row with the pivot. Repeat Step 1-3 again and again until you can’t anymore.
5. Find your rightmost pivot. Make it 1. Then make all the entries above it 0.