Most of what a devops person does is in fact development but it is of the non value adding variety. Basically a devops person spends the vast majority of their time configuring common off the shelf software, scripting this or that, etc.
A singular matrix is a matrix which has no inverse because its determinant is zero. If you recall, the inverse of a matrix is. 1/ ad-bc multiplied by: [ d -b ] [-c a ] If ad-bc = 0, then the inverse matrix would not exist because 1/0 is undefined, and hence it would be a singular matrix. E.g.
A column matrix is formed by a single column. A rectangular matrix is formed by a different number of rows and columns, and its dimension is noted as: mxn. A square matrix is formed by the same number of rows and columns. The elements of the form aii constitute the principal diagonal. The secondary diagonal is formed by the elements with i+j = n+1.