Eigen::symbolic Namespace Reference

This namespace defines a set of classes and functions to build and evaluate symbolic expressions of scalar type Index. More...

Classes
class	AddExpr
class	BaseExpr
	Common base class of any symbolic expressions. More...
struct	is_symbolic
class	NegateExpr
class	ProductExpr
class	QuotientExpr
class	Symbol
class	SymbolExpr
	Expression of a symbol uniquely identified by the template parameter type tag. More...
class	SymbolValue
	Represents the actual value of a symbol identified by its tag. More...
class	ValueExpr
class	ValueExpr< internal::FixedInt< N > >

Detailed Description

This namespace defines a set of classes and functions to build and evaluate symbolic expressions of scalar type Index.

Here is a simple example:

// First step, defines symbols:
struct x_tag {};  static const symbolic::SymbolExpr<x_tag> x;
struct y_tag {};  static const symbolic::SymbolExpr<y_tag> y;
struct z_tag {};  static const symbolic::SymbolExpr<z_tag> z;
 
// Defines an expression:
auto expr = (x+3)/y+z;
 
// And evaluate it: (c++14)
std::cout << expr.eval(x=6,y=3,z=-13) << "\n";
 
// In c++98/11, only one symbol per expression is supported for now:
auto expr98 = (3-x)/2;
std::cout << expr98.eval(x=6) << "\n";

It is currently only used internally to define and manipulate the Eigen::last and Eigen::lastp1 symbols in Eigen::seq and Eigen::seqN.