Determining Pivot Columns in a Matrix - Fred's Question

[mathboy20]

Hi

I got simple question. How is it that determain if a column in matrix is a pivot column?

Sincerely

Fred

 

[NateTG]

I got simple question. How is it that determain if a column in matrix is a pivot column?

Are you asking about gaussian reduction, the simplex method, or something else?

 

[mathboy20]

Are you asking about gaussian reduction, the simplex method, or something else?

What I'm asking given a matrix

A= [[1,2,2,0,1,1][0,i,0,0,1,2][0,0,0,0,i,0][0,0,1,2,2i]]


Which in echelonform gives

A ~[[1,2,2,0,1,1][0,1,0,0,-i,-2i][0,0,1,2,0,2i][0,0,0,0,1,0]]

My question is the pivot column of this matrix aren't they

column 1,2,5,6 ??

Since the definition a pivot position is is the column where there is a non-zero entry above a zero entry??

Best Regards
Mathboy20

 

[NateTG]

For row echelon form, the pivot columns where there is a non-zero value to the right of leading zeros.

In the example you give, the pivot columns would be 1,2,3, and 5.