Пример #1
0
// Solution of KKT equations by a dense LDL factorization of the
// 3 x 3 system.
//
// Returns a function that (1) computes the LDL factorization of
//
// [ H           A'   GG'*W^{-1} ]
// [ A           0    0          ],
// [ W^{-T}*GG   0   -I          ]
//
// given H, Df, W, where GG = [Df; G], and (2) returns a function for
// solving
//
//  [ H     A'   GG'   ]   [ ux ]   [ bx ]
//  [ A     0    0     ] * [ uy ] = [ by ].
//  [ GG    0   -W'*W  ]   [ uz ]   [ bz ]
//
// H is n x n,  A is p x n, Df is mnl x n, G is N x n where
// N = dims['l'] + sum(dims['q']) + sum( k**2 for k in dims['s'] ).
//
func kktLdl(G *matrix.FloatMatrix, dims *sets.DimensionSet, A *matrix.FloatMatrix, mnl int) (kktFactor, error) {

	p, n := A.Size()
	ldK := n + p + mnl + dims.At("l")[0] + dims.Sum("q") + dims.SumPacked("s")
	K := matrix.FloatZeros(ldK, ldK)
	ipiv := make([]int32, ldK)
	u := matrix.FloatZeros(ldK, 1)
	g := matrix.FloatZeros(mnl+G.Rows(), 1)
	//checkpnt.AddMatrixVar("u", u)
	//checkpnt.AddMatrixVar("K", K)

	factor := func(W *sets.FloatMatrixSet, H, Df *matrix.FloatMatrix) (KKTFunc, error) {
		var err error = nil
		// Zero K for each call.
		blas.ScalFloat(K, 0.0)
		if H != nil {
			K.SetSubMatrix(0, 0, H)
		}
		K.SetSubMatrix(n, 0, A)
		for k := 0; k < n; k++ {
			// g is (mnl + G.Rows(), 1) matrix, Df is (mnl, n), G is (N, n)
			if mnl > 0 {
				// set values g[0:mnl] = Df[,k]
				g.SetIndexesFromArray(Df.GetColumnArray(k, nil), matrix.MakeIndexSet(0, mnl, 1)...)
			}
			// set values g[mnl:] = G[,k]
			g.SetIndexesFromArray(G.GetColumnArray(k, nil), matrix.MakeIndexSet(mnl, mnl+g.Rows(), 1)...)
			scale(g, W, true, true)
			if err != nil {
				//fmt.Printf("scale error: %s\n", err)
			}
			pack(g, K, dims, &la.IOpt{"mnl", mnl}, &la.IOpt{"offsety", k*ldK + n + p})
		}
		setDiagonal(K, n+p, n+n, ldK, ldK, -1.0)
		err = lapack.Sytrf(K, ipiv)
		if err != nil {
			return nil, err
		}

		solve := func(x, y, z *matrix.FloatMatrix) (err error) {
			// Solve
			//
			//     [ H          A'   GG'*W^{-1} ]   [ ux   ]   [ bx        ]
			//     [ A          0    0          ] * [ uy   [ = [ by        ]
			//     [ W^{-T}*GG  0   -I          ]   [ W*uz ]   [ W^{-T}*bz ]
			//
			// and return ux, uy, W*uz.
			//
			// On entry, x, y, z contain bx, by, bz.  On exit, they contain
			// the solution ux, uy, W*uz.
			err = nil
			blas.Copy(x, u)
			blas.Copy(y, u, &la.IOpt{"offsety", n})
			err = scale(z, W, true, true)
			if err != nil {
				return
			}
			err = pack(z, u, dims, &la.IOpt{"mnl", mnl}, &la.IOpt{"offsety", n + p})
			if err != nil {
				return
			}

			err = lapack.Sytrs(K, u, ipiv)
			if err != nil {
				return
			}

			blas.Copy(u, x, &la.IOpt{"n", n})
			blas.Copy(u, y, &la.IOpt{"n", p}, &la.IOpt{"offsetx", n})
			err = unpack(u, z, dims, &la.IOpt{"mnl", mnl}, &la.IOpt{"offsetx", n + p})
			return
		}
		return solve, err
	}
	return factor, nil
}