1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
#pragma once
#include "Storage.hh"
#include "NTensor.hh"
namespace cadabra {
/// \ingroup numerical
///
/// Functionality to numerically evaluate a scalar expression,
/// give the values of its building blocks.
///
/// The input is a map which relates subtrees in the expression
/// to numerical values. The `evaluate` function will then do a
/// post-order iteration over the tree, collecting and combining
/// the values thus obtained.
///
/// Currently needs the leaf nodes to have an entry in the
/// `subtree_values` map; may be extended later to cover values
/// of non-elementary subtrees.
///
/// If the input variables are 'a' NTensors, then at any stage...
class NEvaluator {
public:
NEvaluator(const Ex&);
/// If we know the value of a subtree explicitly as a number,
/// it is stored in this map. These are computed nodes.
std::map<Ex::iterator, NTensor, Ex::iterator_base_less> subtree_values;
/// If we know the value of a subtree is equal to another subtree
/// (either in the same expression or another one), it is stored
/// in the map below. This then still needs a lookup in the
/// `subtree_values` map.
std::map<Ex::iterator, Ex::iterator, Ex::iterator_base_less> subtree_equalities;
/// The expression will get evaluated for a range of values for
/// each unknown sub-expression (variable). These are set in
/// the map below.
class VariableValues {
public:
Ex variable;
NTensor values;
std::vector<Ex::iterator> locations;
};
std::vector<VariableValues> variable_values;
/// Set the range of values which we want to insert into the
/// indicated variable. Fills the map above.
void set_variable(const Ex&, const NTensor& val);
/// Evaluate the expression, using the variable values set in
/// `set_variable`.
NTensor evaluate();
/// PRIVATE:
void find_variable_locations();
private:
const Ex& ex;
};
};
|
