\(\newcommand{\W}[1]{ \; #1 \; }\) \(\newcommand{\R}[1]{ {\rm #1} }\) \(\newcommand{\B}[1]{ {\bf #1} }\) \(\newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} }\) \(\newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} }\) \(\newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} }\) \(\newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }\)
atomic_two_eigen_mat_mul.hpp¶
View page sourceatomic_two Eigen Matrix Multiply Class¶
See Also¶
Purpose¶
Construct an atomic operation that computes the matrix product, \(R = A \times \B{R}\) for any positive integers \(r\), \(m\), \(c\), and any \(A \in \B{R}^{r \times m}\), \(B \in \B{R}^{m \times c}\).
Matrix Dimensions¶
This example puts the matrix dimensions in the atomic function arguments, instead of the constructor , so that they can be different for different calls to the atomic function. These dimensions are:
nr_left |
number of rows in the left matrix; i.e, \(r\) |
n_middle |
rows in the left matrix and columns in right; i.e, \(m\) |
nc_right |
number of columns in the right matrix; i.e., \(c\) |
Theory¶
Forward¶
For \(k = 0 , \ldots\), the k-th order Taylor coefficient \(R_k\) is given by
\[R_k = \sum_{\ell = 0}^{k} A_\ell B_{k-\ell}\]
Product of Two Matrices¶
Suppose \(\bar{E}\) is the derivative of the scalar value function \(s(E)\) with respect to \(E\); i.e.,
\[\bar{E}_{i,j} = \frac{ \partial s } { \partial E_{i,j} }\]
Also suppose that \(t\) is a scalar valued argument and
\[E(t) = C(t) D(t)\]
It follows that
\[E'(t) = C'(t) D(t) + C(t) D'(t)\]
\[(s \circ E)'(t)
=
\R{tr} [ \bar{E}^\R{T} E'(t) ]\]
\[=
\R{tr} [ \bar{E}^\R{T} C'(t) D(t) ] +
\R{tr} [ \bar{E}^\R{T} C(t) D'(t) ]\]
\[=
\R{tr} [ D(t) \bar{E}^\R{T} C'(t) ] +
\R{tr} [ \bar{E}^\R{T} C(t) D'(t) ]\]
\[\bar{C} = \bar{E} D^\R{T} \W{,}
\bar{D} = C^\R{T} \bar{E}\]
Reverse¶
Reverse mode eliminates \(R_k\) as follows: for \(\ell = 0, \ldots , k-1\),
\[\bar{A}_\ell = \bar{A}_\ell + \bar{R}_k B_{k-\ell}^\R{T}\]
\[\bar{B}_{k-\ell} = \bar{B}_{k-\ell} + A_\ell^\R{T} \bar{R}_k\]
Start Class Definition¶
# include <cppad/cppad.hpp>
# include <Eigen/Core>
Public¶
Types¶
namespace { // BEGIN_EMPTY_NAMESPACE
template <class Base>
class atomic_eigen_mat_mul : public CppAD::atomic_base<Base> {
public:
// -----------------------------------------------------------
// type of elements during calculation of derivatives
typedef Base scalar;
// type of elements during taping
typedef CppAD::AD<scalar> ad_scalar;
// type of matrix during calculation of derivatives
typedef Eigen::Matrix<
scalar, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor> matrix;
// type of matrix during taping
typedef Eigen::Matrix<
ad_scalar, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor > ad_matrix;
Constructor¶
// constructor
atomic_eigen_mat_mul(void) : CppAD::atomic_base<Base>(
"atom_eigen_mat_mul" ,
CppAD::atomic_base<Base>::set_sparsity_enum
)
{ }
op¶
// use atomic operation to multiply two AD matrices
ad_matrix op(
const ad_matrix& left ,
const ad_matrix& right )
{ size_t nr_left = size_t( left.rows() );
size_t n_middle = size_t( left.cols() );
size_t nc_right = size_t( right.cols() );
assert( n_middle == size_t( right.rows() ) );
size_t nx = 3 + (nr_left + nc_right) * n_middle;
size_t ny = nr_left * nc_right;
size_t n_left = nr_left * n_middle;
size_t n_right = n_middle * nc_right;
size_t n_result = nr_left * nc_right;
//
assert( 3 + n_left + n_right == nx );
assert( n_result == ny );
// -----------------------------------------------------------------
// packed version of left and right
CPPAD_TESTVECTOR(ad_scalar) packed_arg(nx);
//
packed_arg[0] = ad_scalar( nr_left );
packed_arg[1] = ad_scalar( n_middle );
packed_arg[2] = ad_scalar( nc_right );
for(size_t i = 0; i < n_left; i++)
packed_arg[3 + i] = left.data()[i];
for(size_t i = 0; i < n_right; i++)
packed_arg[ 3 + n_left + i ] = right.data()[i];
// ------------------------------------------------------------------
// Packed version of result = left * right.
// This as an atomic_base function call that CppAD uses
// to store the atomic operation on the tape.
CPPAD_TESTVECTOR(ad_scalar) packed_result(ny);
(*this)(packed_arg, packed_result);
// ------------------------------------------------------------------
// unpack result matrix
ad_matrix result(nr_left, nc_right);
for(size_t i = 0; i < n_result; i++)
result.data()[i] = packed_result[ i ];
//
return result;
}
Private¶
Variables¶
private:
// -------------------------------------------------------------
// one forward mode vector of matrices for left, right, and result
CppAD::vector<matrix> f_left_, f_right_, f_result_;
// one reverse mode vector of matrices for left, right, and result
CppAD::vector<matrix> r_left_, r_right_, r_result_;
// -------------------------------------------------------------
forward¶
// forward mode routine called by CppAD
virtual bool forward(
// lowest order Taylor coefficient we are evaluating
size_t p ,
// highest order Taylor coefficient we are evaluating
size_t q ,
// which components of x are variables
const CppAD::vector<bool>& vx ,
// which components of y are variables
CppAD::vector<bool>& vy ,
// tx [ 3 + j * (q+1) + k ] is x_j^k
const CppAD::vector<scalar>& tx ,
// ty [ i * (q+1) + k ] is y_i^k
CppAD::vector<scalar>& ty
)
{ size_t n_order = q + 1;
size_t nr_left = size_t( CppAD::Integer( tx[ 0 * n_order + 0 ] ) );
size_t n_middle = size_t( CppAD::Integer( tx[ 1 * n_order + 0 ] ) );
size_t nc_right = size_t( CppAD::Integer( tx[ 2 * n_order + 0 ] ) );
# ifndef NDEBUG
size_t nx = 3 + (nr_left + nc_right) * n_middle;
size_t ny = nr_left * nc_right;
# endif
//
assert( vx.size() == 0 || nx == vx.size() );
assert( vx.size() == 0 || ny == vy.size() );
assert( nx * n_order == tx.size() );
assert( ny * n_order == ty.size() );
//
size_t n_left = nr_left * n_middle;
size_t n_right = n_middle * nc_right;
size_t n_result = nr_left * nc_right;
assert( 3 + n_left + n_right == nx );
assert( n_result == ny );
//
// -------------------------------------------------------------------
// make sure f_left_, f_right_, and f_result_ are large enough
assert( f_left_.size() == f_right_.size() );
assert( f_left_.size() == f_result_.size() );
if( f_left_.size() < n_order )
{ f_left_.resize(n_order);
f_right_.resize(n_order);
f_result_.resize(n_order);
//
for(size_t k = 0; k < n_order; k++)
{ f_left_[k].resize( long(nr_left), long(n_middle) );
f_right_[k].resize( long(n_middle), long(nc_right) );
f_result_[k].resize( long(nr_left), long(nc_right) );
}
}
// -------------------------------------------------------------------
// unpack tx into f_left and f_right
for(size_t k = 0; k < n_order; k++)
{ // unpack left values for this order
for(size_t i = 0; i < n_left; i++)
f_left_[k].data()[i] = tx[ (3 + i) * n_order + k ];
//
// unpack right values for this order
for(size_t i = 0; i < n_right; i++)
f_right_[k].data()[i] = tx[ ( 3 + n_left + i) * n_order + k ];
}
// -------------------------------------------------------------------
// result for each order
// (we could avoid recalculting f_result_[k] for k=0,...,p-1)
for(size_t k = 0; k < n_order; k++)
{ // result[k] = sum_ell left[ell] * right[k-ell]
f_result_[k] = matrix::Zero( long(nr_left), long(nc_right) );
for(size_t ell = 0; ell <= k; ell++)
f_result_[k] += f_left_[ell] * f_right_[k-ell];
}
// -------------------------------------------------------------------
// pack result_ into ty
for(size_t k = 0; k < n_order; k++)
{ for(size_t i = 0; i < n_result; i++)
ty[ i * n_order + k ] = f_result_[k].data()[i];
}
// ------------------------------------------------------------------
// check if we are computing vy
if( vx.size() == 0 )
return true;
// ------------------------------------------------------------------
// compute variable information for y; i.e., vy
// (note that the constant zero times a variable is a constant)
scalar zero(0.0);
assert( n_order == 1 );
for(size_t i = 0; i < nr_left; i++)
{ for(size_t j = 0; j < nc_right; j++)
{ bool var = false;
for(size_t ell = 0; ell < n_middle; ell++)
{ // left information
size_t index = 3 + i * n_middle + ell;
bool var_left = vx[index];
bool nz_left = var_left |
(f_left_[0]( long(i), long(ell) ) != zero);
// right information
index = 3 + n_left + ell * nc_right + j;
bool var_right = vx[index];
bool nz_right = var_right |
(f_right_[0]( long(ell), long(j) ) != zero);
// effect of result
var |= var_left & nz_right;
var |= nz_left & var_right;
}
size_t index = i * nc_right + j;
vy[index] = var;
}
}
return true;
}
reverse¶
// reverse mode routine called by CppAD
virtual bool reverse(
// highest order Taylor coefficient that we are computing derivative of
size_t q ,
// forward mode Taylor coefficients for x variables
const CppAD::vector<double>& tx ,
// forward mode Taylor coefficients for y variables
const CppAD::vector<double>& ty ,
// upon return, derivative of G[ F[ {x_j^k} ] ] w.r.t {x_j^k}
CppAD::vector<double>& px ,
// derivative of G[ {y_i^k} ] w.r.t. {y_i^k}
const CppAD::vector<double>& py
)
{ size_t n_order = q + 1;
size_t nr_left = size_t( CppAD::Integer( tx[ 0 * n_order + 0 ] ) );
size_t n_middle = size_t( CppAD::Integer( tx[ 1 * n_order + 0 ] ) );
size_t nc_right = size_t( CppAD::Integer( tx[ 2 * n_order + 0 ] ) );
# ifndef NDEBUG
size_t nx = 3 + (nr_left + nc_right) * n_middle;
size_t ny = nr_left * nc_right;
# endif
//
assert( nx * n_order == tx.size() );
assert( ny * n_order == ty.size() );
assert( px.size() == tx.size() );
assert( py.size() == ty.size() );
//
size_t n_left = nr_left * n_middle;
size_t n_right = n_middle * nc_right;
size_t n_result = nr_left * nc_right;
assert( 3 + n_left + n_right == nx );
assert( n_result == ny );
// -------------------------------------------------------------------
// make sure f_left_, f_right_ are large enough
assert( f_left_.size() == f_right_.size() );
assert( f_left_.size() == f_result_.size() );
// must have previous run forward with order >= n_order
assert( f_left_.size() >= n_order );
// -------------------------------------------------------------------
// make sure r_left_, r_right_, and r_result_ are large enough
assert( r_left_.size() == r_right_.size() );
assert( r_left_.size() == r_result_.size() );
if( r_left_.size() < n_order )
{ r_left_.resize(n_order);
r_right_.resize(n_order);
r_result_.resize(n_order);
//
for(size_t k = 0; k < n_order; k++)
{ r_left_[k].resize( long(nr_left), long(n_middle) );
r_right_[k].resize( long(n_middle), long(nc_right) );
r_result_[k].resize( long(nr_left), long(nc_right) );
}
}
// -------------------------------------------------------------------
// unpack tx into f_left and f_right
for(size_t k = 0; k < n_order; k++)
{ // unpack left values for this order
for(size_t i = 0; i < n_left; i++)
f_left_[k].data()[i] = tx[ (3 + i) * n_order + k ];
//
// unpack right values for this order
for(size_t i = 0; i < n_right; i++)
f_right_[k].data()[i] = tx[ (3 + n_left + i) * n_order + k ];
}
// -------------------------------------------------------------------
// unpack py into r_result_
for(size_t k = 0; k < n_order; k++)
{ for(size_t i = 0; i < n_result; i++)
r_result_[k].data()[i] = py[ i * n_order + k ];
}
// -------------------------------------------------------------------
// initialize r_left_ and r_right_ as zero
for(size_t k = 0; k < n_order; k++)
{ r_left_[k] = matrix::Zero( long(nr_left), long(n_middle) );
r_right_[k] = matrix::Zero( long(n_middle), long(nc_right) );
}
// -------------------------------------------------------------------
// matrix reverse mode calculation
for(size_t k1 = n_order; k1 > 0; k1--)
{ size_t k = k1 - 1;
for(size_t ell = 0; ell <= k; ell++)
{ // nr x nm = nr x nc * nc * nm
r_left_[ell] += r_result_[k] * f_right_[k-ell].transpose();
// nm x nc = nm x nr * nr * nc
r_right_[k-ell] += f_left_[ell].transpose() * r_result_[k];
}
}
// -------------------------------------------------------------------
// pack r_left and r_right int px
for(size_t k = 0; k < n_order; k++)
{ // dimensions are integer constants
px[ 0 * n_order + k ] = 0.0;
px[ 1 * n_order + k ] = 0.0;
px[ 2 * n_order + k ] = 0.0;
//
// pack left values for this order
for(size_t i = 0; i < n_left; i++)
px[ (3 + i) * n_order + k ] = r_left_[k].data()[i];
//
// pack right values for this order
for(size_t i = 0; i < n_right; i++)
px[ (3 + i + n_left) * n_order + k] = r_right_[k].data()[i];
}
//
return true;
}
for_sparse_jac¶
// forward Jacobian sparsity routine called by CppAD
virtual bool for_sparse_jac(
// number of columns in the matrix R
size_t q ,
// sparsity pattern for the matrix R
const CppAD::vector< std::set<size_t> >& r ,
// sparsity pattern for the matrix S = f'(x) * R
CppAD::vector< std::set<size_t> >& s ,
const CppAD::vector<Base>& x )
{
size_t nr_left = size_t( CppAD::Integer( x[0] ) );
size_t n_middle = size_t( CppAD::Integer( x[1] ) );
size_t nc_right = size_t( CppAD::Integer( x[2] ) );
# ifndef NDEBUG
size_t nx = 3 + (nr_left + nc_right) * n_middle;
size_t ny = nr_left * nc_right;
# endif
//
assert( nx == r.size() );
assert( ny == s.size() );
//
size_t n_left = nr_left * n_middle;
for(size_t i = 0; i < nr_left; i++)
{ for(size_t j = 0; j < nc_right; j++)
{ // pack index for entry (i, j) in result
size_t i_result = i * nc_right + j;
s[i_result].clear();
for(size_t ell = 0; ell < n_middle; ell++)
{ // pack index for entry (i, ell) in left
size_t i_left = 3 + i * n_middle + ell;
// pack index for entry (ell, j) in right
size_t i_right = 3 + n_left + ell * nc_right + j;
// check if result of for this product is alwasy zero
// note that x is nan for commponents that are variables
bool zero = x[i_left] == Base(0.0) || x[i_right] == Base(0);
if( ! zero )
{ s[i_result] =
CppAD::set_union(s[i_result], r[i_left] );
s[i_result] =
CppAD::set_union(s[i_result], r[i_right] );
}
}
}
}
return true;
}
rev_sparse_jac¶
// reverse Jacobian sparsity routine called by CppAD
virtual bool rev_sparse_jac(
// number of columns in the matrix R^T
size_t q ,
// sparsity pattern for the matrix R^T
const CppAD::vector< std::set<size_t> >& rt ,
// sparsity pattern for the matrix S^T = f'(x)^T * R^T
CppAD::vector< std::set<size_t> >& st ,
const CppAD::vector<Base>& x )
{
size_t nr_left = size_t( CppAD::Integer( x[0] ) );
size_t n_middle = size_t( CppAD::Integer( x[1] ) );
size_t nc_right = size_t( CppAD::Integer( x[2] ) );
size_t nx = 3 + (nr_left + nc_right) * n_middle;
# ifndef NDEBUG
size_t ny = nr_left * nc_right;
# endif
//
assert( nx == st.size() );
assert( ny == rt.size() );
//
// initialize S^T as empty
for(size_t i = 0; i < nx; i++)
st[i].clear();
// sparsity for S(x)^T = f'(x)^T * R^T
size_t n_left = nr_left * n_middle;
for(size_t i = 0; i < nr_left; i++)
{ for(size_t j = 0; j < nc_right; j++)
{ // pack index for entry (i, j) in result
size_t i_result = i * nc_right + j;
st[i_result].clear();
for(size_t ell = 0; ell < n_middle; ell++)
{ // pack index for entry (i, ell) in left
size_t i_left = 3 + i * n_middle + ell;
// pack index for entry (ell, j) in right
size_t i_right = 3 + n_left + ell * nc_right + j;
//
st[i_left] = CppAD::set_union(st[i_left], rt[i_result]);
st[i_right] = CppAD::set_union(st[i_right], rt[i_result]);
}
}
}
return true;
}
for_sparse_hes¶
virtual bool for_sparse_hes(
// which components of x are variables for this call
const CppAD::vector<bool>& vx,
// sparsity pattern for the diagonal of R
const CppAD::vector<bool>& r ,
// sparsity pattern for the vector S
const CppAD::vector<bool>& s ,
// sparsity patternfor the Hessian H(x)
CppAD::vector< std::set<size_t> >& h ,
const CppAD::vector<Base>& x )
{
size_t nr_left = size_t( CppAD::Integer( x[0] ) );
size_t n_middle = size_t( CppAD::Integer( x[1] ) );
size_t nc_right = size_t( CppAD::Integer( x[2] ) );
size_t nx = 3 + (nr_left + nc_right) * n_middle;
# ifndef NDEBUG
size_t ny = nr_left * nc_right;
# endif
//
assert( vx.size() == nx );
assert( r.size() == nx );
assert( s.size() == ny );
assert( h.size() == nx );
//
// initilize h as empty
for(size_t i = 0; i < nx; i++)
h[i].clear();
//
size_t n_left = nr_left * n_middle;
for(size_t i = 0; i < nr_left; i++)
{ for(size_t j = 0; j < nc_right; j++)
{ // pack index for entry (i, j) in result
size_t i_result = i * nc_right + j;
if( s[i_result] )
{ for(size_t ell = 0; ell < n_middle; ell++)
{ // pack index for entry (i, ell) in left
size_t i_left = 3 + i * n_middle + ell;
// pack index for entry (ell, j) in right
size_t i_right = 3 + n_left + ell * nc_right + j;
if( r[i_left] && r[i_right] )
{ h[i_left].insert(i_right);
h[i_right].insert(i_left);
}
}
}
}
}
return true;
}
rev_sparse_hes¶
// reverse Hessian sparsity routine called by CppAD
virtual bool rev_sparse_hes(
// which components of x are variables for this call
const CppAD::vector<bool>& vx,
// sparsity pattern for S(x) = g'[f(x)]
const CppAD::vector<bool>& s ,
// sparsity pattern for d/dx g[f(x)] = S(x) * f'(x)
CppAD::vector<bool>& t ,
// number of columns in R, U(x), and V(x)
size_t q ,
// sparsity pattern for R
const CppAD::vector< std::set<size_t> >& r ,
// sparsity pattern for U(x) = g^{(2)} [ f(x) ] * f'(x) * R
const CppAD::vector< std::set<size_t> >& u ,
// sparsity pattern for
// V(x) = f'(x)^T * U(x) + sum_{i=0}^{m-1} S_i(x) f_i^{(2)} (x) * R
CppAD::vector< std::set<size_t> >& v ,
// parameters as integers
const CppAD::vector<Base>& x )
{
size_t nr_left = size_t( CppAD::Integer( x[0] ) );
size_t n_middle = size_t( CppAD::Integer( x[1] ) );
size_t nc_right = size_t( CppAD::Integer( x[2] ) );
size_t nx = 3 + (nr_left + nc_right) * n_middle;
# ifndef NDEBUG
size_t ny = nr_left * nc_right;
# endif
//
assert( vx.size() == nx );
assert( s.size() == ny );
assert( t.size() == nx );
assert( r.size() == nx );
assert( v.size() == nx );
//
// initilaize return sparsity patterns as false
for(size_t j = 0; j < nx; j++)
{ t[j] = false;
v[j].clear();
}
//
size_t n_left = nr_left * n_middle;
for(size_t i = 0; i < nr_left; i++)
{ for(size_t j = 0; j < nc_right; j++)
{ // pack index for entry (i, j) in result
size_t i_result = i * nc_right + j;
for(size_t ell = 0; ell < n_middle; ell++)
{ // pack index for entry (i, ell) in left
size_t i_left = 3 + i * n_middle + ell;
// pack index for entry (ell, j) in right
size_t i_right = 3 + n_left + ell * nc_right + j;
//
// back propagate T(x) = S(x) * f'(x).
t[i_left] |= bool( s[i_result] );
t[i_right] |= bool( s[i_result] );
//
// V(x) = f'(x)^T * U(x) + sum_i S_i(x) * f_i''(x) * R
// U(x) = g''[ f(x) ] * f'(x) * R
// S_i(x) = g_i'[ f(x) ]
//
// back propagate f'(x)^T * U(x)
v[i_left] = CppAD::set_union(v[i_left], u[i_result] );
v[i_right] = CppAD::set_union(v[i_right], u[i_result] );
//
// back propagate S_i(x) * f_i''(x) * R
// (here is where we use vx to check for cross terms)
if( s[i_result] && vx[i_left] && vx[i_right] )
{ v[i_left] = CppAD::set_union(v[i_left], r[i_right] );
v[i_right] = CppAD::set_union(v[i_right], r[i_left] );
}
}
}
}
return true;
}
End Class Definition¶
}; // End of atomic_eigen_mat_mul class
} // END_EMPTY_NAMESPACE