A row is a summation operation.
A column is an impulse response.
If the inner loop of a matrix multiply ranges within a
row, the operator is called sum or pull.
column, the operator is called spray or push.
A basic aspect of adjointness is that the adjoint of a row matrix operator is a column matrix operator. For example, the row operator [a,b]
The adjoint of a sum of N terms is a collection of N assignments.