** Random sparse matrices. **

** R = SPRANDN(S) has the same sparsity structure as S, but normally **

** distributed random entries. **

** R = SPRANDN(m,n,density) is a random, m-by-n, sparse matrix with **

** approximately density*m*n normally distributed nonzero entries. **

** R = SPRANDN(m,n,density,rc) also has reciprocal condition number **

** approximately equal to rc. R is constructed from a sum of **

** matrices of rank one. **

** **

** **

** If rc is a vector of length lr <= min(m,n), then R has **

** rc as its first lr singular values, all others are zero. **

** In this case, R is generated by random plane rotations **

** applied to a diagonal matrix with the given singular values **

** It has a great deal of topological and algebraic structure. **

** **

** **

** See also SPRANDSYM . **

** **