Express a least squares problem as a larger linear system.
S = SPAUGMENT(A,c) creates the sparse, square, symmetric indefinite
matrix S = [c*I21KTGXR A; A' 0]. This matrix is related to the least
min norm(b - A*x)
r = b - A*x
S * [r/c; x] = [b; 0].
The optimum value of the residual scaling factor c, involves
min(svd(A)) and norm(r), which are usually too expensive to compute.
S = SPAUGMENT(A), without a specified value of c, uses the
default set by SPPARMS , which is usually max(max(abs(A)))/1000.
The augmented matrix is used automatically by the sparse
linear equation solvers, \ and /, for nonsquare problems.
See also SPPARMS .