dirac_trace() can handle arbitrary gamma strings without gamma5. The only

[ginac.git] / ginac / clifford.h

diff --git a/ginac/clifford.h b/ginac/clifford.h
index 86978e98b3846cac2bee5507b1b247f5c1f744ec..f1783396995620d63c1a38f24315675f97476742 100644 (file)
--- a/ginac/clifford.h
+++ b/ginac/clifford.h
@@ -1,6 +1,6 @@
 /** @file clifford.h
  *
- *  Interface to GiNaC's clifford objects. */
+ *  Interface to GiNaC's clifford algebra (Dirac gamma) objects. */
 
 /*
  *  GiNaC Copyright (C) 1999-2001 Johannes Gutenberg University Mainz, Germany
@@ -23,59 +23,117 @@
 #ifndef __GINAC_CLIFFORD_H__
 #define __GINAC_CLIFFORD_H__
 
-#include <string>
-#include "lortensor.h"
+#include "indexed.h"
+#include "tensor.h"
 
 namespace GiNaC {
 
 
 /** This class holds an object representing an element of the Clifford
  *  algebra (the Dirac gamma matrices). These objects only carry Lorentz
- *  indices. Spinor indices are always hidden in our implementation. */
-class clifford : public lortensor
+ *  indices. Spinor indices are hidden. A representation label (an unsigned
+ *  8-bit integer) is used to distinguish elements from different Clifford
+ *  algebras (objects with different labels commute). */
+class clifford : public indexed
 {
-       GINAC_DECLARE_REGISTERED_CLASS(clifford, lortensor)
-
-// friends
-
-       friend clifford clifford_gamma(const ex & mu);
+       GINAC_DECLARE_REGISTERED_CLASS(clifford, indexed)
 
        // other constructors
 public:
-       clifford(const std::string & n, const ex & mu);
-       clifford(const std::string & n, const exvector & iv);
-       clifford(const std::string & n, exvector * ivp);
+       clifford(const ex & b, unsigned char rl = 0);
+       clifford(const ex & b, const ex & mu, unsigned char rl = 0);
+
+       // internal constructors
+       clifford(unsigned char rl, const exvector & v, bool discardable = false);
+       clifford(unsigned char rl, exvector * vp); // vp will be deleted
 
        // functions overriding virtual functions from base classes
-public:
-       void printraw(std::ostream & os) const;
-       void printtree(std::ostream & os, unsigned indent) const;
-       void print(std::ostream & os, unsigned upper_precedence=0) const;
-       bool info(unsigned inf) const;
-       // ex eval(int level=0) const;
 protected:
-       bool is_equal_same_type(const basic & other) const;
        ex simplify_ncmul(const exvector & v) const;
        ex thisexprseq(const exvector & v) const;
        ex thisexprseq(exvector * vp) const;
+       unsigned return_type(void) const { return return_types::noncommutative; }
+       unsigned return_type_tinfo(void) const { return TINFO_clifford + representation_label; }
 
-       // new virtual functions which can be overridden by derived classes
-       // none
-       
        // non-virtual functions in this class
-       // none
+public:
+       unsigned char get_representation_label(void) const {return representation_label;}
 
        // member variables
-       // none
+private:
+       unsigned char representation_label; /**< Representation label to distinguish independent spin lines */
+};
+
+
+/** This class represents the Clifford algebra unity element. */
+class diracone : public tensor
+{
+       GINAC_DECLARE_REGISTERED_CLASS(diracone, tensor)
+
+       // functions overriding virtual functions from bases classes
+public:
+       void print(const print_context & c, unsigned level = 0) const;
+};
+
+
+/** This class represents the Dirac gamma Lorentz vector. */
+class diracgamma : public tensor
+{
+       GINAC_DECLARE_REGISTERED_CLASS(diracgamma, tensor)
+
+       // functions overriding virtual functions from bases classes
+public:
+       void print(const print_context & c, unsigned level = 0) const;
+       bool contract_with(exvector::iterator self, exvector::iterator other, exvector & v) const;
+};
+
+
+/** This class represents the Dirac gamma5 object. */
+class diracgamma5 : public tensor
+{
+       GINAC_DECLARE_REGISTERED_CLASS(diracgamma5, tensor)
+
+       // functions overriding virtual functions from bases classes
+public:
+       void print(const print_context & c, unsigned level = 0) const;
 };
 
+
 // global functions
 inline const clifford &ex_to_clifford(const ex &e)
 {
        return static_cast<const clifford &>(*e.bp);
 }
 
-clifford clifford_gamma(const ex & mu);
+
+/** Create a Clifford unity object.
+ *
+ *  @param rl Representation label
+ *  @return newly constructed object */
+ex dirac_ONE(unsigned char rl = 0);
+
+/** Create a Dirac gamma object.
+ *
+ *  @param mu Index (must be of class varidx or a derived class)
+ *  @param rl Representation label
+ *  @return newly constructed gamma object */
+ex dirac_gamma(const ex & mu, unsigned char rl = 0);
+
+/** Create a Dirac gamma5 object.
+ *
+ *  @param rl Representation label
+ *  @return newly constructed object */
+ex dirac_gamma5(unsigned char rl = 0);
+
+/** Calculate the trace of an expression containing gamma objects with
+ *  a specified representation label. The computed trace is a linear
+ *  functional that is equal to the usual trace only in D = 4 dimensions.
+ *  In particular, the functional is non-cyclic in D != 4 dimensions when
+ *  gamma5 is involved.
+ *
+ *  @param rl Representation label */
+ex dirac_trace(const ex & e, unsigned char rl = 0);
+
 
 } // namespace GiNaC