changedk := true endfor while state≠0 do ! next rotation m := 1 ! find index (k,l) of pivot p for k := 2 to n−1 do if │Sk indk│ > │Sm indm│ then m := k endif endfor k := m; l := indm; p := Skl ! calculate c = cos φ, s = sin φ y := (el−ek)/2; d := │y│+√(p2+y2) r := √(p2+d2); c := d/r; s := p/r; t := p2/d if y<0 then s := −s; t := −t endif Skl := 0.0; update(k,−t); update(l,t) ! rotate rows and columns k and l for i := 1 to k−1 do rotate(i,k,i,l) endfor for i := k+1 to l−1 do rotate(k,i,i,l) endfor for i := l+1 to n do rotate(k,i,l,i) endfor ! rotate eigenvectors for i := 1 to n do ┌ ┐ ┌ ┐┌ ┐ │Eik│ │c −s││Eik│ │ │ := │ ││ │ │Eil│ │s c││Eil│ └ ┘ └ ┘└ ┘ endfor ! update all potentially changed indi for i := 1 to n do indi := maxind(i) endfor loop endproc Notes 1. The logical array changed holds the status of each eigenvalue. If the numerical value of or changes during an iteration, the corresponding component of changed is set to true, otherwise to false. The integer state counts the number of components of changed which have the value true. Iteration stops as soon as state = 0. This means that none of the approximations has recently changed its value and thus it is not very likely that this will happen if iteration continues. Here it is assumed that floating point operations are optimally rounded to the nearest floating point number. 2. The upper triangle of the matrix S is destroyed while the lower triangle and the diagonal are unchanged. Thus it is possible to restore S if necessary according to for k := 1 to n−1 do ! restore matrix S for l := k+1 to n do Skl := Slk endfor endfor 3. The eigenvalues are not necessarily in descending order. This can be achieved by a simple sorting algorithm. for k := 1 to n−1 do m := k for l := k+1 to n do if el > em then m := l endif endfor if k ≠ m then swap em,ek swap Em,Ek endif endfor 4. The algorithm is written using matrix notation (1 based arrays instead of