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atomic_three_mat_mul.hpp¶
View page sourceMatrix Multiply as an Atomic Operation¶
See Also¶
Purpose¶
Use scalar double operations in an atomic_three operation
that computes the matrix product for AD<double operations.
parameter_x¶
This example demonstrates the use of the parameter_x argument to the atomic_three virtual functions.
type_x¶
This example also demonstrates the use of the type_x argument to the atomic_three virtual functions.
Matrix Dimensions¶
The first three components of the argument vector ax in the call afun ( ax , ay ) are parameters and contain the matrix dimensions. This enables them to be different for each use of the same atomic function afun . These dimensions are:
ax [0] |
nr_left |
number of rows in the left matrix and result matrix |
ax [1] |
n_middle |
columns in the left matrix and rows in right matrix |
ax [2] |
nc_right |
number of columns in the right matrix and result matrix |
Left Matrix¶
The number of elements in the left matrix is
n_left = nr_left * n_middle
The elements are in ax [3] through ax [2+ n_left ] in row major order.
Right Matrix¶
The number of elements in the right matrix is
n_right = n_middle * nc_right
The elements are in ax [3+ n_left ] through ax [2+ n_left + n_right ] in row major order.
Result Matrix¶
The number of elements in the result matrix is
n_result = nr_left * nc_right
The elements are in
ay [0] through ay [ n_result -1 ] in row major order.
Start Class Definition¶
# include <cppad/cppad.hpp>
namespace { // Begin empty namespace
using CppAD::vector;
//
// matrix result = left * right
class atomic_mat_mul : public CppAD::atomic_three<double> {
Constructor¶
public:
// ---------------------------------------------------------------------
// constructor
atomic_mat_mul(void) : CppAD::atomic_three<double>("mat_mul")
{ }
private:
Left Operand Element Index¶
Index in the Taylor coefficient matrix tx of a left matrix element.
size_t left(
size_t i , // left matrix row index
size_t j , // left matrix column index
size_t k , // Taylor coeffocient order
size_t nk , // number of Taylor coefficients in tx
size_t nr_left , // rows in left matrix
size_t n_middle , // rows in left and columns in right
size_t nc_right ) // columns in right matrix
{ assert( i < nr_left );
assert( j < n_middle );
return (3 + i * n_middle + j) * nk + k;
}
Right Operand Element Index¶
Index in the Taylor coefficient matrix tx of a right matrix element.
size_t right(
size_t i , // right matrix row index
size_t j , // right matrix column index
size_t k , // Taylor coeffocient order
size_t nk , // number of Taylor coefficients in tx
size_t nr_left , // rows in left matrix
size_t n_middle , // rows in left and columns in right
size_t nc_right ) // columns in right matrix
{ assert( i < n_middle );
assert( j < nc_right );
size_t offset = 3 + nr_left * n_middle;
return (offset + i * nc_right + j) * nk + k;
}
Result Element Index¶
Index in the Taylor coefficient matrix ty of a result matrix element.
size_t result(
size_t i , // result matrix row index
size_t j , // result matrix column index
size_t k , // Taylor coeffocient order
size_t nk , // number of Taylor coefficients in ty
size_t nr_left , // rows in left matrix
size_t n_middle , // rows in left and columns in right
size_t nc_right ) // columns in right matrix
{ assert( i < nr_left );
assert( j < nc_right );
return (i * nc_right + j) * nk + k;
}
Forward Matrix Multiply¶
Forward mode multiply Taylor coefficients in tx and sum into ty (for one pair of left and right orders)
void forward_multiply(
size_t k_left , // order for left coefficients
size_t k_right , // order for right coefficients
const vector<double>& tx , // domain space Taylor coefficients
vector<double>& ty , // range space Taylor coefficients
size_t nr_left , // rows in left matrix
size_t n_middle , // rows in left and columns in right
size_t nc_right ) // columns in right matrix
{
size_t nx = 3 + (nr_left + nc_right) * n_middle;
size_t nk = tx.size() / nx;
# ifndef NDEBUG
size_t ny = nr_left * nc_right;
assert( nk == ty.size() / ny );
# endif
//
size_t k_result = k_left + k_right;
assert( k_result < nk );
//
for(size_t i = 0; i < nr_left; i++)
{ for(size_t j = 0; j < nc_right; j++)
{ double sum = 0.0;
for(size_t ell = 0; ell < n_middle; ell++)
{ size_t i_left = left(
i, ell, k_left, nk, nr_left, n_middle, nc_right
);
size_t i_right = right(
ell, j, k_right, nk, nr_left, n_middle, nc_right
);
sum += tx[i_left] * tx[i_right];
}
size_t i_result = result(
i, j, k_result, nk, nr_left, n_middle, nc_right
);
ty[i_result] += sum;
}
}
}
Reverse Matrix Multiply¶
Reverse mode partials of Taylor coefficients and sum into px (for one pair of left and right orders)
void reverse_multiply(
size_t k_left , // order for left coefficients
size_t k_right , // order for right coefficients
const vector<double>& tx , // domain space Taylor coefficients
const vector<double>& ty , // range space Taylor coefficients
vector<double>& px , // partials w.r.t. tx
const vector<double>& py , // partials w.r.t. ty
size_t nr_left , // rows in left matrix
size_t n_middle , // rows in left and columns in right
size_t nc_right ) // columns in right matrix
{
size_t nx = 3 + (nr_left + nc_right) * n_middle;
size_t nk = tx.size() / nx;
# ifndef NDEBUG
size_t ny = nr_left * nc_right;
assert( nk == ty.size() / ny );
# endif
assert( tx.size() == px.size() );
assert( ty.size() == py.size() );
//
size_t k_result = k_left + k_right;
assert( k_result < nk );
//
for(size_t i = 0; i < nr_left; i++)
{ for(size_t j = 0; j < nc_right; j++)
{ size_t i_result = result(
i, j, k_result, nk, nr_left, n_middle, nc_right
);
for(size_t ell = 0; ell < n_middle; ell++)
{ size_t i_left = left(
i, ell, k_left, nk, nr_left, n_middle, nc_right
);
size_t i_right = right(
ell, j, k_right, nk, nr_left, n_middle, nc_right
);
// sum += tx[i_left] * tx[i_right];
px[i_left] += tx[i_right] * py[i_result];
px[i_right] += tx[i_left] * py[i_result];
}
}
}
return;
}
for_type¶
Routine called by CppAD during afun(ax, ay) .
// calculate type_y
virtual bool for_type(
const vector<double>& parameter_x ,
const vector<CppAD::ad_type_enum>& type_x ,
vector<CppAD::ad_type_enum>& type_y )
{ assert( parameter_x.size() == type_x.size() );
bool ok = true;
ok &= type_x[0] == CppAD::constant_enum;
ok &= type_x[1] == CppAD::constant_enum;
ok &= type_x[2] == CppAD::constant_enum;
if( ! ok )
return false;
//
size_t nr_left = size_t( parameter_x[0] );
size_t n_middle = size_t( parameter_x[1] );
size_t nc_right = size_t( parameter_x[2] );
//
ok &= type_x.size() == 3 + (nr_left + nc_right) * n_middle;
ok &= type_y.size() == n_middle * nc_right;
if( ! ok )
return false;
//
// commpute type_y
size_t nk = 1; // number of orders
size_t k = 0; // order
for(size_t i = 0; i < nr_left; ++i)
{ for(size_t j = 0; j < nc_right; ++j)
{ // compute type for result[i, j]
CppAD::ad_type_enum type_yij = CppAD::constant_enum;
for(size_t ell = 0; ell < n_middle; ++ell)
{ // index for left(i, ell)
size_t i_left = left(
i, ell, k, nk, nr_left, n_middle, nc_right
);
// indx for right(ell, j)
size_t i_right = right(
ell, j, k, nk, nr_left, n_middle, nc_right
);
// multiplication on left or right by the constant zero
// always results in a constant
bool zero_left = type_x[i_left] == CppAD::constant_enum;
zero_left &= parameter_x[i_left] == 0.0;
bool zero_right = type_x[i_right] == CppAD::constant_enum;
zero_right &= parameter_x[i_right] == 0.0;
if( ! (zero_left | zero_right) )
{ type_yij = std::max(type_yij, type_x[i_left] );
type_yij = std::max(type_yij, type_x[i_right] );
}
}
size_t i_result = result(
i, j, k, nk, nr_left, n_middle, nc_right
);
type_y[i_result] = type_yij;
}
}
return true;
}
forward¶
Routine called by CppAD during Forward mode.
virtual bool forward(
const vector<double>& parameter_x ,
const vector<CppAD::ad_type_enum>& type_x ,
size_t need_y ,
size_t q ,
size_t p ,
const vector<double>& tx ,
vector<double>& ty )
{ size_t n_order = p + 1;
size_t nr_left = size_t( tx[ 0 * n_order + 0 ] );
size_t n_middle = size_t( tx[ 1 * n_order + 0 ] );
size_t nc_right = size_t( 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() );
size_t i, j, ell;
// initialize result as zero
size_t k;
for(i = 0; i < nr_left; i++)
{ for(j = 0; j < nc_right; j++)
{ for(k = q; k <= p; k++)
{ size_t i_result = result(
i, j, k, n_order, nr_left, n_middle, nc_right
);
ty[i_result] = 0.0;
}
}
}
for(k = q; k <= p; k++)
{ // sum the produces that result in order k
for(ell = 0; ell <= k; ell++)
forward_multiply(
ell, k - ell, tx, ty, nr_left, n_middle, nc_right
);
}
// all orders are implemented, so always return true
return true;
}
reverse¶
Routine called by CppAD during Reverse mode.
virtual bool reverse(
const vector<double>& parameter_x ,
const vector<CppAD::ad_type_enum>& type_x ,
size_t p ,
const vector<double>& tx ,
const vector<double>& ty ,
vector<double>& px ,
const vector<double>& py )
{ size_t n_order = p + 1;
size_t nr_left = size_t( tx[ 0 * n_order + 0 ] );
size_t n_middle = size_t( tx[ 1 * n_order + 0 ] );
size_t nc_right = size_t( 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() );
// initialize summation
for(size_t i = 0; i < px.size(); i++)
px[i] = 0.0;
// number of orders to differentiate
size_t k = n_order;
while(k--)
{ // differentiate the produces that result in order k
for(size_t ell = 0; ell <= k; ell++)
reverse_multiply(
ell, k - ell, tx, ty, px, py, nr_left, n_middle, nc_right
);
}
// all orders are implented, so always return true
return true;
}
jac_sparsity¶
// Jacobian sparsity routine called by CppAD
virtual bool jac_sparsity(
const vector<double>& parameter_x ,
const vector<CppAD::ad_type_enum>& type_x ,
bool dependency ,
const vector<bool>& select_x ,
const vector<bool>& select_y ,
CppAD::sparse_rc< vector<size_t> >& pattern_out )
{
size_t n = select_x.size();
size_t m = select_y.size();
assert( parameter_x.size() == n );
assert( type_x.size() == n );
//
size_t nr_left = size_t( parameter_x[0] );
size_t n_middle = size_t( parameter_x[1] );
size_t nc_right = size_t( parameter_x[2] );
size_t nk = 1; // only one order
size_t k = 0; // order zero
//
// count number of non-zeros in sparsity pattern
size_t nnz = 0;
for(size_t i = 0; i < nr_left; ++i)
{ for(size_t j = 0; j < nc_right; ++j)
{ size_t i_result = result(
i, j, k, nk, nr_left, n_middle, nc_right
);
if( select_y[i_result] )
{ for(size_t ell = 0; ell < n_middle; ++ell)
{ size_t i_left = left(
i, ell, k, nk, nr_left, n_middle, nc_right
);
size_t i_right = right(
ell, j, k, nk, nr_left, n_middle, nc_right
);
bool zero_left =
type_x[i_left] == CppAD::constant_enum;
zero_left &= parameter_x[i_left] == 0.0;
bool zero_right =
type_x[i_right] == CppAD::constant_enum;
zero_right &= parameter_x[i_right] == 0.0;
if( ! (zero_left | zero_right ) )
{ bool var_left =
type_x[i_left] == CppAD::variable_enum;
bool var_right =
type_x[i_right] == CppAD::variable_enum;
if( select_x[i_left] & var_left )
++nnz;
if( select_x[i_right] & var_right )
++nnz;
}
}
}
}
}
//
// fill in the sparsity pattern
pattern_out.resize(m, n, nnz);
size_t idx = 0;
for(size_t i = 0; i < nr_left; ++i)
{ for(size_t j = 0; j < nc_right; ++j)
{ size_t i_result = result(
i, j, k, nk, nr_left, n_middle, nc_right
);
if( select_y[i_result] )
{ for(size_t ell = 0; ell < n_middle; ++ell)
{ size_t i_left = left(
i, ell, k, nk, nr_left, n_middle, nc_right
);
size_t i_right = right(
ell, j, k, nk, nr_left, n_middle, nc_right
);
bool zero_left =
type_x[i_left] == CppAD::constant_enum;
zero_left &= parameter_x[i_left] == 0.0;
bool zero_right =
type_x[i_right] == CppAD::constant_enum;
zero_right &= parameter_x[i_right] == 0.0;
if( ! (zero_left | zero_right ) )
{ bool var_left =
type_x[i_left] == CppAD::variable_enum;
bool var_right =
type_x[i_right] == CppAD::variable_enum;
if( select_x[i_left] & var_left )
pattern_out.set(idx++, i_result, i_left);
if( select_x[i_right] & var_right )
pattern_out.set(idx++, i_result, i_right);
}
}
}
}
}
assert( idx == nnz );
//
return true;
}
hes_sparsity¶
// Jacobian sparsity routine called by CppAD
virtual bool hes_sparsity(
const vector<double>& parameter_x ,
const vector<CppAD::ad_type_enum>& type_x ,
const vector<bool>& select_x ,
const vector<bool>& select_y ,
CppAD::sparse_rc< vector<size_t> >& pattern_out )
{
size_t n = select_x.size();
assert( parameter_x.size() == n );
assert( type_x.size() == n );
//
size_t nr_left = size_t( parameter_x[0] );
size_t n_middle = size_t( parameter_x[1] );
size_t nc_right = size_t( parameter_x[2] );
size_t nk = 1; // only one order
size_t k = 0; // order zero
//
// count number of non-zeros in sparsity pattern
size_t nnz = 0;
for(size_t i = 0; i < nr_left; ++i)
{ for(size_t j = 0; j < nc_right; ++j)
{ size_t i_result = result(
i, j, k, nk, nr_left, n_middle, nc_right
);
if( select_y[i_result] )
{ for(size_t ell = 0; ell < n_middle; ++ell)
{ // i_left depends on i, ell
size_t i_left = left(
i, ell, k, nk, nr_left, n_middle, nc_right
);
// i_right depens on ell, j
size_t i_right = right(
ell, j, k, nk, nr_left, n_middle, nc_right
);
bool var_left = select_x[i_left] &
(type_x[i_left] == CppAD::variable_enum);
bool var_right = select_x[i_right] &
(type_x[i_right] == CppAD::variable_enum);
if( var_left & var_right )
nnz += 2;
}
}
}
}
//
// fill in the sparsity pattern
pattern_out.resize(n, n, nnz);
size_t idx = 0;
for(size_t i = 0; i < nr_left; ++i)
{ for(size_t j = 0; j < nc_right; ++j)
{ size_t i_result = result(
i, j, k, nk, nr_left, n_middle, nc_right
);
if( select_y[i_result] )
{ for(size_t ell = 0; ell < n_middle; ++ell)
{ size_t i_left = left(
i, ell, k, nk, nr_left, n_middle, nc_right
);
size_t i_right = right(
ell, j, k, nk, nr_left, n_middle, nc_right
);
bool var_left = select_x[i_left] &
(type_x[i_left] == CppAD::variable_enum);
bool var_right = select_x[i_right] &
(type_x[i_right] == CppAD::variable_enum);
if( var_left & var_right )
{ // Cannot possibly set the same (i_left, i_right)
// pair twice.
assert( i_left != i_right );
pattern_out.set(idx++, i_left, i_right);
pattern_out.set(idx++, i_right, i_left);
}
}
}
}
}
assert( idx == nnz );
//
return true;
}
rev_depend¶
Routine called when a function using mat_mul is optimized.
// calculate depend_x
virtual bool rev_depend(
const vector<double>& parameter_x ,
const vector<CppAD::ad_type_enum>& type_x ,
vector<bool>& depend_x ,
const vector<bool>& depend_y )
{ assert( parameter_x.size() == depend_x.size() );
assert( parameter_x.size() == type_x.size() );
bool ok = true;
//
size_t nr_left = size_t( parameter_x[0] );
size_t n_middle = size_t( parameter_x[1] );
size_t nc_right = size_t( parameter_x[2] );
//
ok &= depend_x.size() == 3 + (nr_left + nc_right) * n_middle;
ok &= depend_y.size() == n_middle * nc_right;
if( ! ok )
return false;
//
// initialize depend_x
for(size_t ell = 0; ell < 3; ++ell)
depend_x[ell] = true; // always need these parameters
for(size_t ell = 3; ell < depend_x.size(); ++ell)
depend_x[ell] = false; // initialize as false
//
// commpute depend_x
size_t nk = 1; // number of orders
size_t k = 0; // order
for(size_t i = 0; i < nr_left; ++i)
{ for(size_t j = 0; j < nc_right; ++j)
{ // check depend for result[i, j]
size_t i_result = result(
i, j, k, nk, nr_left, n_middle, nc_right
);
if( depend_y[i_result] )
{ for(size_t ell = 0; ell < n_middle; ++ell)
{ // index for left(i, ell)
size_t i_left = left(
i, ell, k, nk, nr_left, n_middle, nc_right
);
// indx for right(ell, j)
size_t i_right = right(
ell, j, k, nk, nr_left, n_middle, nc_right
);
bool zero_left =
type_x[i_left] == CppAD::constant_enum;
zero_left &= parameter_x[i_left] == 0.0;
bool zero_right =
type_x[i_right] == CppAD::constant_enum;
zero_right &= parameter_x[i_right] == 0.0;
if( ! zero_right )
depend_x[i_left] = true;
if( ! zero_left )
depend_x[i_right] = true;
}
}
}
}
return true;
}
End Class Definition¶
}; // End of mat_mul class
} // End empty namespace