Golang cmat.NewFloatConstSource函數代碼示例

func TestDTrmmUnitUpper(t *testing.T) {
	var d cmat.FloatMatrix
	N := 563
	K := 171

	A := cmat.NewMatrix(N, N)
	B := cmat.NewMatrix(N, K)
	B0 := cmat.NewMatrix(N, K)
	C := cmat.NewMatrix(N, K)

	zeros := cmat.NewFloatConstSource(0.0)
	ones := cmat.NewFloatConstSource(1.0)
	zeromean := cmat.NewFloatNormSource()

	A.SetFrom(zeromean, cmat.UPPER|cmat.UNIT)
	B.SetFrom(ones)
	B0.SetFrom(ones)
	// B = A*B
	blasd.MultTrm(B, A, 1.0, gomas.UPPER|gomas.LEFT|gomas.UNIT)
	d.Diag(A).SetFrom(ones)
	blasd.Mult(C, A, B0, 1.0, 0.0, gomas.NONE)
	ok := C.AllClose(B)
	t.Logf("trmm(B, A, L|U|N|U) == gemm(C, TriUU(A), B)   : %v\n", ok)

	B.SetFrom(ones)
	// B = A.T*B
	d.Diag(A).SetFrom(zeros)
	blasd.MultTrm(B, A, 1.0, gomas.UPPER|gomas.LEFT|gomas.TRANSA|gomas.UNIT)
	d.Diag(A).SetFrom(ones)
	blasd.Mult(C, A, B0, 1.0, 0.0, gomas.TRANSA)
	ok = C.AllClose(B)
	t.Logf("trmm(B, A, L|U|T|U) == gemm(C, TriUU(A).T, B) : %v\n", ok)
}

func TestDTrmmUnitUpperRight(t *testing.T) {
	var d cmat.FloatMatrix
	N := 563
	K := 171

	A := cmat.NewMatrix(N, N)
	B := cmat.NewMatrix(K, N)
	B0 := cmat.NewMatrix(K, N)
	C := cmat.NewMatrix(K, N)

	zeros := cmat.NewFloatConstSource(0.0)
	ones := cmat.NewFloatConstSource(1.0)
	zeromean := cmat.NewFloatNormSource()

	A.SetFrom(zeromean, cmat.UPPER|cmat.UNIT)
	B.SetFrom(ones)
	B0.SetFrom(ones)
	// B = B*A
	blasd.MultTrm(B, A, 1.0, gomas.UPPER|gomas.RIGHT|gomas.UNIT)
	d.Diag(A).SetFrom(ones)
	blasd.Mult(C, B0, A, 1.0, 0.0, gomas.NONE)
	ok := C.AllClose(B)
	t.Logf("trmm(B, A, R|U|N|U) == gemm(C, B, TriUU(A))   : %v\n", ok)

	B.SetFrom(ones)
	// B = B*A.T
	d.SetFrom(zeros)
	blasd.MultTrm(B, A, 1.0, gomas.UPPER|gomas.RIGHT|gomas.TRANSA|gomas.UNIT)
	d.SetFrom(ones)
	blasd.Mult(C, B0, A, 1.0, 0.0, gomas.TRANSB)
	ok = C.AllClose(B)
	t.Logf("trmm(B, A, R|U|T|U) == gemm(C, B, TriUU(A).T) : %v\n", ok)
}

// Simple and slow LQ decomposition with Givens rotations
func TestGivensLQ(t *testing.T) {
	var d cmat.FloatMatrix
	M := 149
	N := 167
	A := cmat.NewMatrix(M, N)
	A1 := cmat.NewCopy(A)

	ones := cmat.NewFloatConstSource(1.0)
	src := cmat.NewFloatNormSource()
	A.SetFrom(src)
	A0 := cmat.NewCopy(A)

	Qt := cmat.NewMatrix(N, N)
	d.Diag(Qt)
	d.SetFrom(ones)

	// R = G(n)...G(2)G(1)*A; Q = G(1).T*G(2).T...G(n).T ;  Q.T = G(n)...G(2)G(1)
	for i := 0; i < M; i++ {
		// zero elements right of diagonal
		for j := N - 2; j >= i; j-- {
			c, s, r := lapackd.ComputeGivens(A.Get(i, j), A.Get(i, j+1))
			A.Set(i, j, r)
			A.Set(i, j+1, 0.0)
			// apply rotation to this column starting from row i+1
			lapackd.ApplyGivensRight(A, j, j+1, i+1, M-i-1, c, s)
			// update Qt = G(k)*Qt
			lapackd.ApplyGivensRight(Qt, j, j+1, 0, N, c, s)
		}
	}
	// A = L*Q
	blasd.Mult(A1, A, Qt, 1.0, 0.0, gomas.TRANSB)
	blasd.Plus(A0, A1, 1.0, -1.0, gomas.NONE)
	nrm := lapackd.NormP(A0, lapackd.NORM_ONE)
	t.Logf("M=%d, N=%d ||A - L*G(1)..G(n)||_1: %e\n", M, N, nrm)
}

func TestDTrsm3(t *testing.T) {
	const N = 31
	const K = 4

	A := cmat.NewMatrix(N, N)
	B := cmat.NewMatrix(N, K)
	B0 := cmat.NewMatrix(N, K)

	ones := cmat.NewFloatConstSource(1.0)
	zeromean := cmat.NewFloatUniformSource(1.0, -0.5)

	A.SetFrom(zeromean, cmat.UPPER)
	B.SetFrom(ones)
	B0.Copy(B)
	// B = A*B
	blasd.MultTrm(B, A, 1.0, gomas.UPPER|gomas.LEFT)
	blasd.SolveTrm(B, A, 1.0, gomas.UPPER|gomas.LEFT)
	ok := B0.AllClose(B)
	t.Logf("B == trsm(trmm(B, A, L|U|N), A, L|U|N) : %v\n", ok)

	B.Copy(B0)
	// B = A.T*B
	blasd.MultTrm(B, A, 1.0, gomas.UPPER|gomas.LEFT|gomas.TRANSA)
	blasd.SolveTrm(B, A, 1.0, gomas.UPPER|gomas.LEFT|gomas.TRANSA)
	ok = B0.AllClose(B)
	t.Logf("B == trsm(trmm(B, A, L|U|T), A, L|U|T) : %v\n", ok)
}

func TestDTrmmLower(t *testing.T) {
	N := 563
	K := 171
	nofail := true

	A := cmat.NewMatrix(N, N)
	B := cmat.NewMatrix(N, K)
	B0 := cmat.NewMatrix(N, K)
	C := cmat.NewMatrix(N, K)

	ones := cmat.NewFloatConstSource(1.0)
	zeromean := cmat.NewFloatNormSource()

	A.SetFrom(zeromean, cmat.LOWER)
	B.SetFrom(ones)
	B0.SetFrom(ones)
	// B = A*B
	blasd.MultTrm(B, A, 1.0, gomas.LOWER|gomas.LEFT)
	blasd.Mult(C, A, B0, 1.0, 0.0, gomas.NONE)
	ok := C.AllClose(B)
	nofail = nofail && ok
	t.Logf("trmm(B, A, L|L|N) == gemm(C, TriL(A), B)   : %v\n", ok)

	B.SetFrom(ones)
	// B = A.T*B
	blasd.MultTrm(B, A, 1.0, gomas.LOWER|gomas.LEFT|gomas.TRANSA)
	blasd.Mult(C, A, B0, 1.0, 0.0, gomas.TRANSA)
	ok = C.AllClose(B)
	nofail = nofail && ok
	t.Logf("trmm(B, A, L|L|T) == gemm(C, TriL(A).T, B) : %v\n", ok)
}

func TestDTrmmLowerRight(t *testing.T) {
	N := 563
	K := 171
	nofail := true

	A := cmat.NewMatrix(N, N)
	B := cmat.NewMatrix(K, N)
	B0 := cmat.NewMatrix(K, N)
	C := cmat.NewMatrix(K, N)

	ones := cmat.NewFloatConstSource(1.0)
	zeromean := cmat.NewFloatNormSource()

	A.SetFrom(zeromean, cmat.LOWER)
	B.SetFrom(ones)
	B0.SetFrom(ones)
	// B = B*A
	blasd.MultTrm(B, A, 1.0, gomas.LOWER|gomas.RIGHT)
	blasd.Mult(C, B0, A, 1.0, 0.0, gomas.NONE)
	ok := C.AllClose(B)
	nofail = nofail && ok
	t.Logf("trmm(B, A, R|L|N) == gemm(C, B, TriL(A))   : %v\n", ok)

	B.SetFrom(ones)
	// B = B*A.T
	blasd.MultTrm(B, A, 1.0, gomas.LOWER|gomas.RIGHT|gomas.TRANSA)
	blasd.Mult(C, B0, A, 1.0, 0.0, gomas.TRANSB)
	ok = C.AllClose(B)
	nofail = nofail && ok
	t.Logf("trmm(B, A, R|L|T) == gemm(C, B, TriL(A).T) : %v\n", ok)
}

/*
 * Solve a system of linear equations A*X = B with general M-by-N
 * matrix A using the QR factorization computed by DecomposeQRT().
 *
 * If flags&gomas.TRANS != 0:
 *   find the minimum norm solution of an overdetermined system A.T * X = B.
 *   i.e min ||X|| s.t A.T*X = B
 *
 * Otherwise:
 *   find the least squares solution of an overdetermined system, i.e.,
 *   solve the least squares problem: min || B - A*X ||.
 *
 * Arguments:
 *  B     On entry, the right hand side N-by-P matrix B. On exit, the solution matrix X.
 *
 *  A     The elements on and above the diagonal contain the min(M,N)-by-N upper
 *        trapezoidal matrix R. The elements below the diagonal with the matrix 'T',
 *        represent the ortogonal matrix Q as product of elementary reflectors.
 *        Matrix A and T are as returned by DecomposeQRT()
 *
 *  T     The block reflector computed from elementary reflectors as returned by
 *        DecomposeQRT() or computed from elementary reflectors and scalar coefficients
 *        by BuildT()
 *
 *  W     Workspace, size as returned by WorkspaceMultQT()
 *
 *  flags Indicator flag
 *
 *  conf  Blocking configuration
 *
 * Compatible with lapack.GELS (the m >= n part)
 */
func QRTSolve(B, A, T, W *cmat.FloatMatrix, flags int, confs ...*gomas.Config) *gomas.Error {
	var err *gomas.Error = nil
	var R, BT cmat.FloatMatrix
	conf := gomas.CurrentConf(confs...)

	if flags&gomas.TRANS != 0 {
		// Solve overdetermined system A.T*X = B

		// B' = R.-1*B
		R.SubMatrix(A, 0, 0, n(A), n(A))
		BT.SubMatrix(B, 0, 0, n(A), n(B))
		err = blasd.SolveTrm(&BT, &R, 1.0, gomas.LEFT|gomas.UPPER|gomas.TRANSA, conf)

		// Clear bottom part of B
		BT.SubMatrix(B, n(A), 0)
		BT.SetFrom(cmat.NewFloatConstSource(0.0))

		// X = Q*B'
		err = QRTMult(B, A, T, W, gomas.LEFT, conf)
	} else {
		// solve least square problem min ||A*X - B||

		// B' = Q.T*B
		err = QRTMult(B, A, T, W, gomas.LEFT|gomas.TRANS, conf)
		if err != nil {
			return err
		}

		// X = R.-1*B'
		R.SubMatrix(A, 0, 0, n(A), n(A))
		BT.SubMatrix(B, 0, 0, n(A), n(B))
		err = blasd.SolveTrm(&BT, &R, 1.0, gomas.LEFT|gomas.UPPER, conf)
	}
	return err
}

func TestDTrsm1(t *testing.T) {
	nofail := true

	const N = 31
	const K = 4

	A := cmat.NewMatrix(N, N)
	B := cmat.NewMatrix(N, K)
	B0 := cmat.NewMatrix(N, K)

	ones := cmat.NewFloatConstSource(1.0)
	zeromean := cmat.NewFloatUniformSource(1.0, -0.5)

	A.SetFrom(zeromean, cmat.LOWER)
	B.SetFrom(ones)
	B0.Copy(B)
	// B = A*B
	blasd.MultTrm(B, A, 1.0, gomas.LOWER|gomas.LEFT)
	blasd.SolveTrm(B, A, 1.0, gomas.LOWER|gomas.LEFT)
	ok := B0.AllClose(B)
	nofail = nofail && ok
	t.Logf("B == trsm(trmm(B, A, L|L|N), A, L|L|N) : %v\n", ok)
	if !ok {
		t.Logf("B|B0:\n%v\n", cmat.NewJoin(cmat.AUGMENT, B, B0))
	}

	B.Copy(B0)
	// B = A.T*B
	blasd.MultTrm(B, A, 1.0, gomas.LOWER|gomas.LEFT|gomas.TRANSA)
	blasd.SolveTrm(B, A, 1.0, gomas.LOWER|gomas.LEFT|gomas.TRANSA)
	ok = B0.AllClose(B)
	nofail = nofail && ok
	t.Logf("B == trsm(trmm(B, A, L|L|T), A, L|L|T) : %v\n", ok)
}

func TestDTrms2(t *testing.T) {
	const N = 31
	const K = 4

	nofail := true

	A := cmat.NewMatrix(N, N)
	B := cmat.NewMatrix(K, N)
	B0 := cmat.NewMatrix(K, N)

	ones := cmat.NewFloatConstSource(1.0)
	zeromean := cmat.NewFloatUniformSource(1.0, -0.5)

	A.SetFrom(zeromean, cmat.LOWER)
	B.SetFrom(ones)
	B0.Copy(B)

	// B = B*A
	blasd.MultTrm(B, A, 1.0, gomas.LOWER|gomas.RIGHT)
	blasd.SolveTrm(B, A, 1.0, gomas.LOWER|gomas.RIGHT)
	ok := B0.AllClose(B)
	nofail = nofail && ok
	t.Logf("B == trsm(trmm(B, A, R|L|N), A, R|L|N) : %v\n", ok)

	B.Copy(B0)
	// B = B*A.T
	blasd.MultTrm(B, A, 1.0, gomas.LOWER|gomas.RIGHT|gomas.TRANSA)
	blasd.SolveTrm(B, A, 1.0, gomas.LOWER|gomas.RIGHT|gomas.TRANSA)
	ok = B0.AllClose(B)
	nofail = nofail && ok
	t.Logf("B == trsm(trmm(B, A, R|L|T), A, R|L|T) : %v\n", ok)
}

func TestPartition2D(t *testing.T) {
	var ATL, ATR, ABL, ABR, As cmat.FloatMatrix
	var A00, a01, A02, a10, a11, a12, A20, a21, A22 cmat.FloatMatrix

	csource := cmat.NewFloatConstSource(1.0)
	A := cmat.NewMatrix(6, 6)
	As.SubMatrix(A, 1, 1, 4, 4)
	As.SetFrom(csource)

	Partition2x2(&ATL, &ATR, &ABL, &ABR, &As, 0, 0, PTOPLEFT)
	t.Logf("ATL:\n%v\n", &ATL)

	t.Logf("n(ATL)=%d, n(As)=%d\n", n(&ATL), n(&As))
	k := 0
	for n(&ATL) < n(&As) && k < n(&As) {
		Repartition2x2to3x3(&ATL,
			&A00, &a01, &A02,
			&a10, &a11, &a12,
			&A20, &a21, &A22, &As, 1, PBOTTOMRIGHT)
		t.Logf("n(A00)=%d, n(a01)=%d, n(A02)=%d\n", n(&A00), n(&a01), n(&A02))
		t.Logf("n(a10)=%d, n(a11)=%d, n(a12)=%d\n", n(&a10), n(&a11), n(&a12))
		t.Logf("n(A20)=%d, n(a21)=%d, n(A22)=%d\n", n(&A20), n(&a21), n(&A22))
		//t.Logf("n(a12)=%d [%d], n(a11)=%d\n", n(&a12), a12.Len(), a11.Len())
		a11.Set(0, 0, a11.Get(0, 0)+1.0)
		addConst(&a21, -2.0)

		Continue3x3to2x2(&ATL, &ATR, &ABL, &ABR, &A00, &a11, &A22, &As, PBOTTOMRIGHT)
		t.Logf("n(ATL)=%d, n(As)=%d\n", n(&ATL), n(&As))
		k += 1
	}
	t.Logf("A:\n%v\n", A)
}

func TestDSyr2(t *testing.T) {

	const N = 911

	A := cmat.NewMatrix(N, N)
	X := cmat.NewMatrix(N, 1)
	Y := cmat.NewMatrix(N, 1)
	B := cmat.NewMatrix(N, N)

	ones := cmat.NewFloatConstSource(1.0)
	twos := cmat.NewFloatConstSource(2.0)
	zeromean := cmat.NewFloatUniformSource(0.5, 2.0)

	A.SetFrom(zeromean, cmat.LOWER)
	X.SetFrom(ones)
	Y.SetFrom(twos)
	B.Copy(A)

	// B = A*B
	blasd.MVUpdate(B, X, Y, 1.0)
	blasd.MVUpdate(B, Y, X, 1.0)
	cmat.TriL(B, cmat.NONE)
	blasd.MVUpdate2Sym(A, X, Y, 1.0, gomas.LOWER)
	ok := B.AllClose(A)
	if N < 10 {
		t.Logf("A:\n%v\n", A)
		t.Logf("B:\n%v\n", B)
	}
	t.Logf("MVUpdate2Sym(A, X, Y, L) == TriL(MVUpdate(A, X, Y);MVUpdate(A, Y, X)) : %v\n", ok)

	A.SetFrom(zeromean, cmat.UPPER)
	cmat.TriU(A, cmat.NONE)
	B.Copy(A)
	blasd.MVUpdate(B, X, Y, 1.0)
	blasd.MVUpdate(B, Y, X, 1.0)
	cmat.TriU(B, cmat.NONE)
	blasd.MVUpdate2Sym(A, X, Y, 1.0, gomas.UPPER)
	ok = B.AllClose(A)
	if N < 10 {
		t.Logf("A:\n%v\n", A)
		t.Logf("B:\n%v\n", B)
	}
	t.Logf("MVUpdate2Sym(A, X, Y, U) == TriU(MVUpdate(A, X, Y);MVUpdate(A, Y, X)) : %v\n", ok)
}

// test: C = C*Q.T
func TestQLMultRightTrans(t *testing.T) {
	var d, di0, di1 cmat.FloatMatrix
	M := 891
	N := 853
	lb := 36
	conf := gomas.NewConf()

	A := cmat.NewMatrix(M, N)
	src := cmat.NewFloatNormSource()
	A.SetFrom(src)

	C0 := cmat.NewMatrix(N, M)
	d.Diag(C0, M-N)
	ones := cmat.NewFloatConstSource(1.0)
	d.SetFrom(ones)
	C1 := cmat.NewCopy(C0)

	I0 := cmat.NewMatrix(N, N)
	I1 := cmat.NewCopy(I0)
	di0.Diag(I0)
	di1.Diag(I1)

	tau := cmat.NewMatrix(N, 1)
	W := cmat.NewMatrix(lb*(M+N), 1)

	conf.LB = lb
	lapackd.QLFactor(A, tau, W, conf)

	conf.LB = 0
	lapackd.QLMult(C0, A, tau, W, gomas.RIGHT|gomas.TRANS, conf)
	// I = Q*Q.T - I
	blasd.Mult(I0, C0, C0, 1.0, 0.0, gomas.TRANSB, conf)
	blasd.Add(&di0, -1.0)
	n0 := lapackd.NormP(I0, lapackd.NORM_ONE)

	conf.LB = lb
	lapackd.QLMult(C1, A, tau, W, gomas.RIGHT|gomas.TRANS, conf)
	// I = Q*Q.T - I
	blasd.Mult(I1, C1, C1, 1.0, 0.0, gomas.TRANSB, conf)
	blasd.Add(&di1, -1.0)
	n1 := lapackd.NormP(I1, lapackd.NORM_ONE)

	if N < 10 {
		t.Logf("unblk C0*Q:\n%v\n", C0)
		t.Logf("blk. C2*Q:\n%v\n", C1)
	}
	blasd.Plus(C0, C1, 1.0, -1.0, gomas.NONE)
	n2 := lapackd.NormP(C0, lapackd.NORM_ONE)

	t.Logf("M=%d, N=%d ||unblk.QLMult(C) - blk.QLMult(C)||_1: %e\n", M, N, n2)
	t.Logf("unblk M=%d, N=%d ||I - Q*Q.T||_1: %e\n", M, N, n0)
	t.Logf("blk   M=%d, N=%d ||I - Q*Q.T||_1: %e\n", M, N, n1)
}

// test: A - Q*Hess(A)*Q.T  == 0
func TestMultHess(t *testing.T) {
	N := 377
	nb := 16

	conf := gomas.NewConf()
	conf.LB = nb

	A := cmat.NewMatrix(N, N)
	tau := cmat.NewMatrix(N, 1)
	zeromean := cmat.NewFloatNormSource()
	A.SetFrom(zeromean)
	A0 := cmat.NewCopy(A)

	// reduction
	W := lapackd.Workspace(lapackd.HessReduceWork(A, conf))
	lapackd.HessReduce(A, tau, W, conf)

	var Hlow cmat.FloatMatrix
	H := cmat.NewCopy(A)

	// set triangular part below first subdiagonal to zeros
	zeros := cmat.NewFloatConstSource(0.0)
	Hlow.SubMatrix(H, 1, 0, N-1, N-1)
	Hlow.SetFrom(zeros, cmat.LOWER|cmat.UNIT)
	H1 := cmat.NewCopy(H)

	// H := Q*H*Q.T
	conf.LB = nb
	lapackd.HessMult(H, A, tau, W, gomas.LEFT, conf)
	lapackd.HessMult(H, A, tau, W, gomas.RIGHT|gomas.TRANS, conf)

	// H := Q*H*Q.T
	conf.LB = 0
	lapackd.HessMult(H1, A, tau, W, gomas.LEFT, conf)
	lapackd.HessMult(H1, A, tau, W, gomas.RIGHT|gomas.TRANS, conf)

	// compute ||Q*Hess(A)*Q.T - A||_1
	blasd.Plus(H, A0, 1.0, -1.0, gomas.NONE)
	nrm := lapackd.NormP(H, lapackd.NORM_ONE)
	t.Logf("  blk.|| Q*Hess(A)*Q.T - A ||_1 : %e\n", nrm)

	blasd.Plus(H1, A0, 1.0, -1.0, gomas.NONE)
	nrm = lapackd.NormP(H1, lapackd.NORM_ONE)
	t.Logf("unblk.|| Q*Hess(A)*Q.T - A ||_1 : %e\n", nrm)
}

/*
 * Solve a system of linear equations A.T*X = B with general M-by-N
 * matrix A using the QR factorization computed by LQFactor().
 *
 * If flags&TRANS != 0:
 *   find the minimum norm solution of an overdetermined system A.T * X = B.
 *   i.e min ||X|| s.t A.T*X = B
 *
 * Otherwise:
 *   find the least squares solution of an overdetermined system, i.e.,
 *   solve the least squares problem: min || B - A*X ||.
 *
 * Arguments:
 *  B     On entry, the right hand side N-by-P matrix B. On exit, the solution matrix X.
 *
 *  A     The elements on and below the diagonal contain the M-by-min(M,N) lower
 *        trapezoidal matrix L. The elements right of the diagonal with the vector 'tau',
 *        represent the ortogonal matrix Q as product of elementary reflectors.
 *        Matrix A is as returned by LQFactor()
 *
 *  tau   The vector of N scalar coefficients that together with trilu(A) define
 *        the ortogonal matrix Q as Q = H(N)H(N-1)...H(1)
 *
 *  W     Workspace, size required returned WorksizeMultLQ().
 *
 *  flags Indicator flags
 *
 *  conf  Optinal blocking configuration. If not given default will be used. Unblocked
 *        invocation is indicated with conf.LB == 0.
 *
 * Compatible with lapack.GELS (the m < n part)
 */
func LQSolve(B, A, tau, W *cmat.FloatMatrix, flags int, confs ...*gomas.Config) *gomas.Error {
	var err *gomas.Error = nil
	var L, BL cmat.FloatMatrix

	conf := gomas.CurrentConf(confs...)

	wsmin := wsMultLQLeft(B, 0)
	if W.Len() < wsmin {
		return gomas.NewError(gomas.EWORK, "SolveLQ", wsmin)
	}

	if flags&gomas.TRANS != 0 {
		// solve: MIN ||A.T*X - B||

		// B' = Q.T*B
		err = LQMult(B, A, tau, W, gomas.LEFT, conf)
		if err != nil {
			return err
		}

		// X = L.-1*B'
		L.SubMatrix(A, 0, 0, m(A), m(A))
		BL.SubMatrix(B, 0, 0, m(A), n(B))
		err = blasd.SolveTrm(&BL, &L, 1.0, gomas.LEFT|gomas.LOWER|gomas.TRANSA, conf)

	} else {
		// Solve underdetermined system A*X = B

		// B' = L.-1*B
		L.SubMatrix(A, 0, 0, m(A), m(A))
		BL.SubMatrix(B, 0, 0, m(A), n(B))
		err = blasd.SolveTrm(&BL, &L, 1.0, gomas.LEFT|gomas.LOWER, conf)

		// Clear bottom part of B
		BL.SubMatrix(B, m(A), 0)
		BL.SetFrom(cmat.NewFloatConstSource(0.0))

		// X = Q.T*B'
		err = LQMult(B, A, tau, W, gomas.LEFT|gomas.TRANS, conf)

	}
	return err
}

func TestCopy(t *testing.T) {
	M := 9
	N := 9
	A := cmat.NewMatrix(M, N)
	B := cmat.NewMatrix(M, N)
	twos := cmat.NewFloatConstSource(2.0)
	B.SetFrom(twos)
	A.Copy(B)
	ok := A.AllClose(B)
	if !ok {
		t.Logf("copy status: %v\n", ok)
		if N < 9 {
			t.Logf("A\n%v\n", A)
		}
	}
	if N < 10 {
		t.Logf("A\n%v\n", A)
	}
}