Golang matrix.Matrix類代碼示例

/*
 Solution of a triangular and banded set of equations.

 Tbsv(A, X, uplo=PLower, trans=PNoTrans, diag=PNonDiag, n=A.Cols,
 k=max(0,A.Rows-1), ldA=A.size[0], incx=1, offsetA=0, offsetx=0)

PURPOSE
  X := A^{-1}*X, if trans is PNoTrans
  X := A^{-T}*X, if trans is PTrans
  X := A^{-H}*X, if trans is PConjTrans

 A is banded triangular of order n and with bandwidth k.

 ARGUMENTS
  A         float or complex m*k matrix.
  X         float or complex k*1 matrix. Must have the same type as A.

 OPTIONS
  uplo      PLower   or PUpper
  trans     PNoTrans, PTrans or PConjTrans
  diag      PNoNUnit or PUnit
  n         nonnegative integer.  If negative, the default value is used.
  k         nonnegative integer.  If negative, the default value is used.
  ldA       nonnegative integer.  ldA >= 1+k.
            If zero the default value is used.
  incx      nonzero integer
  offsetA   nonnegative integer
  offsetx   nonnegative integer;
*/
func Tbsv(A, X matrix.Matrix, opts ...linalg.Option) (err error) {

	var params *linalg.Parameters
	if !matrix.EqualTypes(A, X) {
		err = errors.New("Parameters not of same type")
		return
	}
	params, err = linalg.GetParameters(opts...)
	if err != nil {
		return
	}
	ind := linalg.GetIndexOpts(opts...)
	err = check_level2_func(ind, ftbsv, X, nil, A, params)
	if err != nil {
		return
	}
	if ind.N == 0 {
		return
	}
	switch X.(type) {
	case *matrix.FloatMatrix:
		Xa := X.FloatArray()
		Aa := A.FloatArray()
		uplo := linalg.ParamString(params.Uplo)
		trans := linalg.ParamString(params.Trans)
		diag := linalg.ParamString(params.Diag)
		dtbsv(uplo, trans, diag, ind.N, ind.K,
			Aa[ind.OffsetA:], ind.LDa, Xa[ind.OffsetX:], ind.IncX)
	case *matrix.ComplexMatrix:
		return errors.New("Not implemented yet for complx.Matrix")
	default:
		return errors.New("Unknown type, not implemented")
	}
	return
}

func checkSyevd(ind *linalg.IndexOpts, A, W matrix.Matrix) error {
	if ind.N < 0 {
		ind.N = A.Rows()
		if ind.N != A.Cols() {
			return errors.New("Syevd: A not square")
		}
	}
	if ind.N == 0 {
		return nil
	}
	if ind.LDa == 0 {
		ind.LDa = max(1, A.Rows())
	}
	if ind.LDa < max(1, ind.N) {
		return errors.New("Syevd: lda")
	}
	if ind.OffsetA < 0 {
		return errors.New("Syevd: offsetA")
	}
	sizeA := A.NumElements()
	if sizeA < ind.OffsetA+(ind.N-1)*ind.LDa+ind.N {
		return errors.New("Syevd: sizeA")
	}
	if ind.OffsetW < 0 {
		return errors.New("Syevd: offsetW")
	}
	sizeW := W.NumElements()
	if sizeW < ind.OffsetW+ind.N {
		return errors.New("Syevd: sizeW")
	}
	return nil
}

/*
 Symmetric rank-2 update.
 syr2(x, y, A, uplo='L', alpha=1.0, n=A.size[0], incx=1, incy=1,
     ldA=max(1,A.size[0]), offsetx=0, offsety=0, offsetA=0)
 PURPOSE
 Computes A := A + alpha*(x*y^T + y*x^T) with A real symmetric matrix of order n.
 ARGUMENTS
 x         float matrix
 y         float matrix
 A         float matrix
 alpha     real number (int or float)

 OPTIONS
 uplo      'L' or 'U'
 n         integer.  If negative, the default value is used.
 incx      nonzero integer
 incy      nonzero integer
 ldA       nonnegative integer.  ldA >= max(1,n).
           If zero the default value is used.
 offsetx   nonnegative integer
 offsety   nonnegative integer
 offsetA   nonnegative integer;
*/
func Syr2(X, Y, A matrix.Matrix, alpha matrix.Scalar, opts ...linalg.Option) (err error) {

	var params *linalg.Parameters
	params, err = linalg.GetParameters(opts...)
	if err != nil {
		return
	}
	ind := linalg.GetIndexOpts(opts...)
	err = check_level2_func(ind, fsyr2, X, Y, A, params)
	if err != nil {
		return
	}
	if !matrix.EqualTypes(A, X, Y) {
		return errors.New("Parameters not of same type")
	}
	switch X.(type) {
	case *matrix.FloatMatrix:
		Xa := X.FloatArray()
		Ya := X.FloatArray()
		Aa := A.FloatArray()
		aval := alpha.Float()
		if math.IsNaN(aval) {
			return errors.New("alpha not a number")
		}
		uplo := linalg.ParamString(params.Uplo)
		dsyr2(uplo, ind.N, aval, Xa[ind.OffsetX:], ind.IncX,
			Ya[ind.OffsetY:], ind.IncY,
			Aa[ind.OffsetA:], ind.LDa)
	case *matrix.ComplexMatrix:
		return errors.New("Not implemented yet for complx.Matrix")
	default:
		return errors.New("Unknown type, not implemented")
	}
	return
}

// Scales a vector by a constant (X := alpha*X).
//
// ARGUMENTS
//  X         float or complex matrix
//  alpha     number (float or complex singleton matrix).  Complex alpha is only
//            allowed if X is complex.
// 
// OPTIONS
//  n         integer.  If n<0, the default value of n is used.
//            The default value is equal to 1+(len(x)-offset-1)/inc or 0
//            if len(x) > offset+1.
//  inc       positive integer, default = 1
//  offset    nonnegative integer, default = 0
//
func Scal(X matrix.Matrix, alpha matrix.Scalar, opts ...linalg.Option) (err error) {
	ind := linalg.GetIndexOpts(opts...)
	err = check_level1_func(ind, fscal, X, nil)
	if err != nil {
		return
	}
	if ind.Nx == 0 {
		return
	}
	switch X.(type) {
	case *matrix.ComplexMatrix:
		Xa := X.ComplexArray()
		cval := alpha.Complex()
		zscal(ind.Nx, cval, Xa[ind.OffsetX:], ind.IncX)
	case *matrix.FloatMatrix:
		Xa := X.FloatArray()
		rval := alpha.Float()
		if math.IsNaN(rval) {
			return errors.New("alpha not float value")
		}
		dscal(ind.Nx, rval, Xa[ind.OffsetX:], ind.IncX)
	default:
		err = errors.New("not implemented for parameter types", )
	}
	return
}

/*
 Inverse of a real or complex matrix.

 Getri(A, ipiv, n=A.Rows, ldA = max(1,A.Rows), offsetA=0)

 PURPOSE

 Computes the inverse of real or complex matrix of order n.  On
 entry, A and ipiv contain the LU factorization, as returned by
 gesv() or getrf().  On exit A is replaced by the inverse.

 ARGUMENTS
  A         float or complex matrix
  ipiv      int vector

 OPTIONS
  n         nonnegative integer.  If negative, the default value is used.
  ldA       positive integer.  ldA >= max(1,n).  If zero, the default
            value is used.
  offsetA   nonnegative integer;
*/
func Getri(A matrix.Matrix, ipiv []int32, opts ...linalg.Option) error {
	ind := linalg.GetIndexOpts(opts...)
	if ind.N < 0 {
		ind.N = A.Cols()
	}
	if ind.N == 0 {
		return nil
	}
	if ind.LDa == 0 {
		ind.LDa = max(1, A.Rows())
	}
	if ind.OffsetA < 0 {
		return errors.New("lda")
	}
	sizeA := A.NumElements()
	if sizeA < ind.OffsetA+(ind.N-1)*ind.LDa+ind.N {
		return errors.New("sizeA")
	}
	if ipiv != nil && len(ipiv) < ind.N {
		return errors.New("size ipiv")
	}
	info := -1
	switch A.(type) {
	case *matrix.FloatMatrix:
		Aa := A.FloatArray()
		info = dgetri(ind.N, Aa[ind.OffsetA:], ind.LDa, ipiv)
	case *matrix.ComplexMatrix:
	}
	if info != 0 {
		return errors.New("Getri call error")
	}
	return nil
}

// Returns Y = X^H*Y for real or complex X, Y.
//
// ARGUMENTS
//  X         float or complex matrix
//  Y         float or complex matrix.  Must have the same type as X.
//
// OPTIONS
//  n         integer.  If n<0, the default value of n is used.
//            The default value is equal to nx = 1+(len(x)-offsetx-1)/incx or 0 if
//            len(x) > offsetx+1.  If the default value is used, it must be equal to
//            ny = 1+(len(y)-offsetx-1)/|incy| or 0 if len(y) > offsety+1
//  incx      nonzero integer [default=1]
//  incy      nonzero integer [default=1]
//  offsetx   nonnegative integer [default=0]
//  offsety   nonnegative integer [default=0]
//
func Dot(X, Y matrix.Matrix, opts ...linalg.Option) (v matrix.Scalar) {
	v = matrix.FScalar(math.NaN())
	//cv = cmplx.NaN()
	ind := linalg.GetIndexOpts(opts...)
	err := check_level1_func(ind, fdot, X, Y)
	if err != nil {
		return
	}
	if ind.Nx == 0 {
		return matrix.FScalar(0.0)
	}
	sameType := matrix.EqualTypes(X, Y)
	if ! sameType {
		err = errors.New("arrays not of same type")
		return
	}
	switch X.(type) {
	case *matrix.ComplexMatrix:
		Xa := X.ComplexArray()
		Ya := Y.ComplexArray()
		v = matrix.CScalar(zdotc(ind.Nx, Xa[ind.OffsetX:], ind.IncX, Ya[ind.OffsetY:], ind.IncY))
	case *matrix.FloatMatrix:
		Xa := X.FloatArray()
		Ya := Y.FloatArray()
		v = matrix.FScalar(ddot(ind.Nx, Xa[ind.OffsetX:], ind.IncX, Ya[ind.OffsetY:], ind.IncY))
	//default:
	//	err = errors.New("not implemented for parameter types", )
	}
	return
}

// Copies a vector X to a vector Y (Y := X).
//
// ARGUMENTS
//  X         float or complex matrix
//  Y         float or complex matrix.  Must have the same type as X.
//
// OPTIONS
//  n         integer.  If n<0, the default value of n is used.
//            The default value is given by 1+(len(x)-offsetx-1)/incx or 0
//            if len(x) > offsetx+1
//  incx      nonzero integer
//  incy      nonzero integer
//  offsetx   nonnegative integer
//  offsety   nonnegative integer;
//
func Copy(X, Y matrix.Matrix, opts ...linalg.Option) (err error) {
	ind := linalg.GetIndexOpts(opts...)
	err = check_level1_func(ind, fcopy, X, Y)
	if err != nil {
		return
	}
	if ind.Nx == 0 {
		return
	}
	sameType := matrix.EqualTypes(X, Y)
	if ! sameType {
		err = errors.New("arrays not same type")
		return
	}
	switch X.(type) {
	case *matrix.ComplexMatrix:
		Xa := X.ComplexArray()
		Ya := Y.ComplexArray()
		zcopy(ind.Nx, Xa[ind.OffsetX:], ind.IncX, Ya[ind.OffsetY:], ind.IncY)
	case *matrix.FloatMatrix:
		Xa := X.FloatArray()
		Ya := Y.FloatArray()
		dcopy(ind.Nx, Xa[ind.OffsetX:], ind.IncX, Ya[ind.OffsetY:], ind.IncY)
	default:
		err = errors.New("not implemented for parameter types", )
	}
	return
}

func checkSytrf(ind *linalg.IndexOpts, A matrix.Matrix, ipiv []int32) error {
	if ind.N < 0 {
		ind.N = A.Rows()
		if ind.N != A.Cols() {
			return errors.New("A not square")
		}
	}
	if ind.N == 0 {
		return nil
	}
	if ind.LDa == 0 {
		ind.LDa = max(1, A.Rows())
	}
	if ind.LDa < max(1, ind.N) {
		return errors.New("Sytrf: lda")
	}
	if ind.OffsetA < 0 {
		return errors.New("Sytrf: offsetA")
	}
	sizeA := A.NumElements()
	if sizeA < ind.OffsetA+(ind.N-1)*ind.LDa+ind.N {
		return errors.New("Sytrf: sizeA")
	}
	if ipiv != nil && len(ipiv) < ind.N {
		return errors.New("Sytrf: size ipiv")
	}
	return nil
}

// Returns ||Re x||_1 + ||Im x||_1.
//
// ARGUMENTS
//  X       float or complex matrix
// 
// OPTIONS
//  n       integer.  If n<0, the default value of n is used.
//          The default value is equal to n = 1+(len(x)-offset-1)/inc or 0 if
//          len(x) > offset+1
//  inc     positive integer
//  offset  nonnegative integer
//
func Asum(X matrix.Matrix, opts ...linalg.Option) (v matrix.Scalar) {
	v = matrix.FScalar(math.NaN())
	ind := linalg.GetIndexOpts(opts...)
	err := check_level1_func(ind, fasum, X, nil)
	if err != nil {
		return
	}
	if ind.Nx == 0 {
		return
	}
	switch X.(type) {
	case *matrix.ComplexMatrix:
		Xa := X.ComplexArray()
		v = matrix.FScalar(dzasum(ind.Nx, Xa[ind.OffsetX:], ind.IncX))
	case *matrix.FloatMatrix:
		Xa := X.FloatArray()
		v =  matrix.FScalar(dasum(ind.Nx, Xa[ind.OffsetX:], ind.IncX))
	//default:
	//	err = errors.New("not implemented for parameter types", )
	}
	return
}

/*
 Rank-k update of symmetric matrix. (L3)

 Herk(A, C, alpha, beta, uplo=PLower, trans=PNoTrans,  n=-1,
 k=-1, ldA=max(1,A.Rows), ldC=max(1,C.Rows), offsetA=0, offsetB=0)

 Computes
  C := alpha*A*A^T + beta*C, if trans is PNoTrans
  C := alpha*A^T*A + beta*C, if trans is PTrans

 C is symmetric (real or complex) of order n. The inner dimension of the matrix
 product is k.  If k=0 this is interpreted as C := beta*C.

 ARGUMENTS
  A         float or complex matrix.
  C         float or complex matrix.  Must have the same type as A.
  alpha     number (float or complex singleton matrix).  Complex alpha is only
            allowed if A is complex.
  beta      number (float or complex singleton matrix).  Complex beta is only
            allowed if A is complex.

 OPTIONS
  uplo      PLower or PUpper
  trans     PNoTrans or PTrans
  n         integer.  If negative, the default value is used.
            The default value is n = A.Rows or if trans == PNoTrans n = A.Cols.
  k         integer.  If negative, the default value is used.
            The default value is k =  A.Cols, or if trans == PNoTrans k = A.Rows.
  ldA       nonnegative integer.
            ldA >= max(1,n) or if trans != PNoTrans ldA >= max(1,k).
            If zero, the default value is used.
  ldC       nonnegative integer.  ldC >= max(1,n).
            If zero, the default value is used.
  offsetA   nonnegative integer
  offsetC   nonnegative integer;
*/
func Herk(A, C matrix.Matrix, alpha, beta matrix.Scalar, opts ...linalg.Option) (err error) {

	params, e := linalg.GetParameters(opts...)
	if e != nil {
		err = e
		return
	}
	ind := linalg.GetIndexOpts(opts...)
	err = check_level3_func(ind, fsyrk, A, nil, C, params)
	if e != nil || err != nil {
		return
	}
	if !matrix.EqualTypes(A, C) {
		return errors.New("Parameters not of same type")
	}
	switch A.(type) {
	case *matrix.FloatMatrix:
		Aa := A.FloatArray()
		Ca := C.FloatArray()
		aval := alpha.Float()
		bval := beta.Float()
		if math.IsNaN(aval) || math.IsNaN(bval) {
			return errors.New("alpha or beta not a number")
		}
		uplo := linalg.ParamString(params.Uplo)
		trans := linalg.ParamString(params.Trans)
		dsyrk(uplo, trans, ind.N, ind.K, aval, Aa[ind.OffsetA:], ind.LDa, bval,
			Ca[ind.OffsetC:], ind.LDc)
	case *matrix.ComplexMatrix:
		Aa := A.ComplexArray()
		Ca := C.ComplexArray()
		aval := alpha.Complex()
		if cmplx.IsNaN(aval) {
			return errors.New("alpha not a real or complex number")
		}
		bval := beta.Float()
		if math.IsNaN(bval) {
			return errors.New("beta not a real number")
		}
		uplo := linalg.ParamString(params.Uplo)
		trans := linalg.ParamString(params.Trans)
		zherk(uplo, trans, ind.N, ind.K, aval, Aa[ind.OffsetA:], ind.LDa, bval,
			Ca[ind.OffsetC:], ind.LDc)
	default:
		return errors.New("Unknown type, not implemented")
	}

	return
}

/*
 Solution of a triangular system of equations with multiple righthand sides. (L3)

 Trsm(A, B, alpha, side=PLeft, uplo=PLower, transA=PNoTrans, diag=PNonUnit,
 m=-1, n=-1, ldA=max(1,A.Rows), ldB=max(1,B.Rows), offsetA=0, offsetB=0)

 Computes
  B := alpha*A^{-1}*B if transA is PNoTrans   and side = PLeft
  B := alpha*B*A^{-1} if transA is PNoTrans   and side = PRight
  B := alpha*A^{-T}*B if transA is PTrans     and side = PLeft
  B := alpha*B*A^{-T} if transA is PTrans     and side = PRight
  B := alpha*A^{-H}*B if transA is PConjTrans and side = PLeft
  B := alpha*B*A^{-H} if transA is PConjTrans and side = PRight

 B is m by n and A is triangular.  The code does not verify whether A is nonsingular.

 ARGUMENTS
  A         float or complex matrix.
  B         float or complex matrix.  Must have the same type as A.
  alpha     number (float or complex).  Complex alpha is only
            allowed if A is complex.

 OPTIONS
  side      PLeft or PRight
  uplo      PLower or PUpper
  transA    PNoTrans or PTrans
  diag      PNonUnit or PUnit
  m         integer.  If negative, the default value is used.
            The default value is m = A.Rows or if side == PRight m = B.Rows
            If the default value is used and side is PLeft, m must be equal to A.Cols.
  n         integer.  If negative, the default value is used.
            The default value is n = B.Cols or if side )= PRight n = A.Rows.
            If the default value is used and side is PRight, n must be equal to A.Cols.
  ldA       nonnegative integer.
            ldA >= max(1,m) of if  side == PRight lda >= max(1,n).
            If zero, the default value is used.
  ldB       nonnegative integer.  ldB >= max(1,m).
            If zero, the default value is used.
  offsetA   nonnegative integer
  offsetB   nonnegative integer
*/
func Trsm(A, B matrix.Matrix, alpha matrix.Scalar, opts ...linalg.Option) (err error) {

	params, e := linalg.GetParameters(opts...)
	if e != nil {
		err = e
		return
	}
	ind := linalg.GetIndexOpts(opts...)
	err = check_level3_func(ind, ftrsm, A, B, nil, params)
	if err != nil {
		return
	}
	if !matrix.EqualTypes(A, B) {
		return errors.New("Parameters not of same type")
	}
	switch A.(type) {
	case *matrix.FloatMatrix:
		Aa := A.FloatArray()
		Ba := B.FloatArray()
		aval := alpha.Float()
		if math.IsNaN(aval) {
			return errors.New("alpha or beta not a number")
		}
		uplo := linalg.ParamString(params.Uplo)
		transA := linalg.ParamString(params.TransA)
		side := linalg.ParamString(params.Side)
		diag := linalg.ParamString(params.Diag)
		dtrsm(side, uplo, transA, diag, ind.M, ind.N, aval,
			Aa[ind.OffsetA:], ind.LDa, Ba[ind.OffsetB:], ind.LDb)
	case *matrix.ComplexMatrix:
		Aa := A.ComplexArray()
		Ba := B.ComplexArray()
		aval := alpha.Complex()
		if cmplx.IsNaN(aval) {
			return errors.New("alpha  not a number")
		}
		uplo := linalg.ParamString(params.Uplo)
		transA := linalg.ParamString(params.TransA)
		side := linalg.ParamString(params.Side)
		diag := linalg.ParamString(params.Diag)
		ztrsm(side, uplo, transA, diag, ind.M, ind.N, aval,
			Aa[ind.OffsetA:], ind.LDa, Ba[ind.OffsetB:], ind.LDb)
	default:
		return errors.New("Unknown type, not implemented")
	}
	return
}

// Constant times a vector plus a vector (Y := alpha*X+Y).
//
// ARGUMENTS
//   X         float or complex matrix
//   Y         float or complex matrix.  Must have the same type as X.
//   alpha     number (float or complex singleton matrix).  Complex alpha is only
//             allowed if x is complex.
//
// OPTIONS
//   n         integer.  If n<0, the default value of n is used.
//             The default value is equal to 1+(len(x)-offsetx-1)/incx 
//             or 0 if  len(x) >= offsetx+1 
//   incx      nonzero integer
//   incy      nonzero integer
//   offsetx   nonnegative integer
//   offsety   nonnegative integer;
//
func Axpy(X, Y matrix.Matrix, alpha matrix.Scalar, opts ...linalg.Option) (err error) {
	ind := linalg.GetIndexOpts(opts...)
	err = check_level1_func(ind, faxpy, X, Y)
	if err != nil {
		return
	}
	if ind.Nx == 0 {
		return
	}
	sameType := matrix.EqualTypes(X, Y)
	if ! sameType {
		err = errors.New("arrays not same type")
		return
	}
	switch X.(type) {
	case *matrix.ComplexMatrix:
		Xa := X.ComplexArray()
		Ya := Y.ComplexArray()
		aval := alpha.Complex()
		if cmplx.IsNaN(aval) {
			return errors.New("alpha not complex value")
		}
		zaxpy(ind.Nx, aval, Xa[ind.OffsetX:],
			ind.IncX, Ya[ind.OffsetY:], ind.IncY)
	case *matrix.FloatMatrix:
		Xa := X.FloatArray()
		Ya := Y.FloatArray()
		aval := alpha.Float()
		if math.IsNaN(aval) {
			return errors.New("alpha not float value")
		}
		daxpy(ind.Nx, aval, Xa[ind.OffsetX:],
			ind.IncX, Ya[ind.OffsetY:], ind.IncY)
	default:
		err = errors.New("not implemented for parameter types", )
	}
	return
}

func checkGbtrf(ind *linalg.IndexOpts, A matrix.Matrix, ipiv []int32) error {
	if ind.M < 0 {
		return errors.New("Gbtrf: illegal m")
	}
	if ind.Kl < 0 {
		return errors.New("GBtrf: illegal kl")
	}
	if ind.N < 0 {
		ind.N = A.Rows()
	}
	if ind.M == 0 || ind.N == 0 {
		return nil
	}
	if ind.Ku < 0 {
		ind.Ku = A.Rows() - 2*ind.Kl - 1
	}
	if ind.Ku < 0 {
		return errors.New("Gbtrf: invalid ku")
	}
	if ind.LDa == 0 {
		ind.LDa = max(1, A.Rows())
	}
	if ind.LDa < 2*ind.Kl+ind.Ku+1 {
		return errors.New("Gbtrf: lda")
	}
	if ind.OffsetA < 0 {
		return errors.New("Gbtrf: offsetA")
	}
	sizeA := A.NumElements()
	if sizeA < ind.OffsetA+(ind.N-1)*ind.LDa+2*ind.Kl+ind.Ku+1 {
		return errors.New("Gbtrf: sizeA")
	}
	if ipiv != nil && len(ipiv) < min(ind.N, ind.M) {
		return errors.New("Gbtrf: size ipiv")
	}
	return nil
}

func checkPotrf(ind *linalg.IndexOpts, A matrix.Matrix) error {
	if ind.N < 0 {
		ind.N = A.Rows()
		if ind.N != A.Cols() {
			return errors.New("Potrf: not square")
		}
	}
	if ind.N == 0 {
		return nil
	}
	if ind.LDa == 0 {
		ind.LDa = max(1, A.Rows())
	}
	if ind.LDa < max(1, ind.N) {
		return errors.New("Potrf: lda")
	}
	if ind.OffsetA < 0 {
		return errors.New("Potrf: offsetA")
	}
	if A.NumElements() < ind.OffsetA+(ind.N-1)*ind.LDa+ind.N {
		return errors.New("Potrf: sizeA")
	}
	return nil
}

/*
 Matrix-vector product with a general banded matrix. (L2)

 Computes
   Y := alpha*A*X + beta*Y,   if trans = PNoTrans
   Y := alpha*A^T*X + beta*Y, if trans = PTrans
   Y := beta*y,               if n=0, m>0, and trans = PNoTrans
   Y := beta*y,               if n>0, m=0, and trans = PTrans

 The matrix A is m by n with upper bandwidth ku and lower bandwidth kl.
 Returns immediately if n=0 and trans is 'Trans', or if m=0 and trans is 'N'.


 ARGUMENTS
   X         float n*1 matrix.
   Y         float m*1 matrix
   A         float m*n matrix.
   alpha     number (float).
   beta      number (float).

 OPTIONS
   trans     NoTrans or Trans
   m         nonnegative integer, default A.Rows()
   kl        nonnegative integer
   n         nonnegative integer.  If negative, the default value is used.
   ku        nonnegative integer.  If negative, the default value is used.
   ldA       positive integer.  ldA >= kl+ku+1. If zero, the default value is used.
   incx      nonzero integer, default =1
   incy      nonzero integer, default =1
   offsetA   nonnegative integer, default =0
   offsetx   nonnegative integer, default =0
   offsety   nonnegative integer, default =0

*/
func Gbmv(A, X, Y matrix.Matrix, alpha, beta matrix.Scalar, opts ...linalg.Option) (err error) {

	var params *linalg.Parameters
	params, err = linalg.GetParameters(opts...)
	if err != nil {
		return
	}
	ind := linalg.GetIndexOpts(opts...)
	err = check_level2_func(ind, fgbmv, X, Y, A, params)
	if err != nil {
		return
	}
	if ind.M == 0 && ind.N == 0 {
		return
	}
	if !matrix.EqualTypes(A, X, Y) {
		return errors.New("Parameters not of same type")
	}
	switch X.(type) {
	case *matrix.FloatMatrix:
		Xa := X.FloatArray()
		Ya := Y.FloatArray()
		Aa := A.FloatArray()
		aval := alpha.Float()
		bval := beta.Float()
		if math.IsNaN(aval) || math.IsNaN(bval) {
			return errors.New("alpha or beta not a number")
		}
		if params.Trans == linalg.PNoTrans && ind.N == 0 {
			dscal(ind.M, bval, Ya[ind.OffsetY:], ind.IncY)
		} else if params.Trans == linalg.PTrans && ind.M == 0 {
			dscal(ind.N, bval, Ya[ind.OffsetY:], ind.IncY)
		} else {
			trans := linalg.ParamString(params.Trans)
			dgbmv(trans, ind.M, ind.N, ind.Kl, ind.Ku,
				aval, Aa[ind.OffsetA:], ind.LDa, Xa[ind.OffsetX:], ind.IncX,
				bval, Ya[ind.OffsetY:], ind.IncY)
		}
	case *matrix.ComplexMatrix:
		return errors.New("Not implemented yet for complx.Matrix")
	default:
		return errors.New("Unknown type, not implemented")
	}
	return
}