X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Ftensor.h;h=3fae6b425a87d768b72cfc7053b5efdc7a6d0154;hp=b077ee4d0c927d8e459250bb0092773b8c876163;hb=15e9408c64b6e9309a9f2388fd91f34101b52f40;hpb=43e0a8f5ca5e1c48cef5daaf014acdbca4e44568

diff --git a/ginac/tensor.h b/ginac/tensor.h
index b077ee4d..3fae6b42 100644
--- a/ginac/tensor.h
+++ b/ginac/tensor.h
@@ -3,7 +3,7 @@
  *  Interface to GiNaC's special tensors. */
 
 /*
- *  GiNaC Copyright (C) 1999-2001 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2002 Johannes Gutenberg University Mainz, Germany
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -37,11 +37,18 @@ class tensor : public basic
 
 	// other constructors
 protected:
-	tensor(unsigned ti);
+	tensor(unsigned ti) : inherited(ti) {}
 
-	// functions overriding virtual functions from bases classes
+	// functions overriding virtual functions from base classes
 protected:
 	unsigned return_type(void) const { return return_types::noncommutative_composite; }
+
+	// non-virtual functions in this class
+public:
+	/** Replace dummy index in contracted-with object by the contracting
+	 *  object's second index (used internally for delta and metric tensor
+	 *  contractions. */
+	bool replace_contr_index(exvector::iterator self, exvector::iterator other) const;
 };
 
 
@@ -51,7 +58,7 @@ class tensdelta : public tensor
 {
 	GINAC_DECLARE_REGISTERED_CLASS(tensdelta, tensor)
 
-	// functions overriding virtual functions from bases classes
+	// functions overriding virtual functions from base classes
 public:
 	void print(const print_context & c, unsigned level = 0) const;
 	ex eval_indexed(const basic & i) const;
@@ -66,7 +73,7 @@ class tensmetric : public tensor
 {
 	GINAC_DECLARE_REGISTERED_CLASS(tensmetric, tensor)
 
-	// functions overriding virtual functions from bases classes
+	// functions overriding virtual functions from base classes
 public:
 	void print(const print_context & c, unsigned level = 0) const;
 	ex eval_indexed(const basic & i) const;
@@ -86,7 +93,7 @@ public:
 	/** Construct Lorentz metric tensor with given signature. */
 	minkmetric(bool pos_sig);
 
-	// functions overriding virtual functions from bases classes
+	// functions overriding virtual functions from base classes
 public:
 	void print(const print_context & c, unsigned level = 0) const;
 	ex eval_indexed(const basic & i) const;
@@ -97,6 +104,22 @@ private:
 };
 
 
+/** This class represents an antisymmetric spinor metric tensor which
+ *  can be used to raise/lower indices of 2-component Weyl spinors. If
+ *  indexed, it must have exactly two indices of the same type which
+ *  must be of class spinidx or a subclass and have dimension 2. */
+class spinmetric : public tensmetric
+{
+	GINAC_DECLARE_REGISTERED_CLASS(spinmetric, tensmetric)
+
+	// functions overriding virtual functions from base classes
+public:
+	void print(const print_context & c, unsigned level = 0) const;
+	ex eval_indexed(const basic & i) const;
+	bool contract_with(exvector::iterator self, exvector::iterator other, exvector & v) const;
+};
+
+
 /** This class represents the totally antisymmetric epsilon tensor. If
  *  indexed, all indices must be of the same type and their number must
  *  be equal to the dimension of the index space. */
@@ -108,10 +131,11 @@ class tensepsilon : public tensor
 public:
 	tensepsilon(bool minkowski, bool pos_sig);
 
-	// functions overriding virtual functions from bases classes
+	// functions overriding virtual functions from base classes
 public:
 	void print(const print_context & c, unsigned level = 0) const;
 	ex eval_indexed(const basic & i) const;
+	bool contract_with(exvector::iterator self, exvector::iterator other, exvector & v) const;
 
 	// member variables
 private:
@@ -121,10 +145,6 @@ private:
 
 
 // utility functions
-inline const tensor &ex_to_tensor(const ex &e)
-{
-	return static_cast<const tensor &>(*e.bp);
-}
 
 /** Create a delta tensor with specified indices. The indices must be of class
  *  idx or a subclass. The delta tensor is always symmetric and its trace is
@@ -155,6 +175,16 @@ ex metric_tensor(const ex & i1, const ex & i2);
  *  @return newly constructed Lorentz metric tensor */
 ex lorentz_g(const ex & i1, const ex & i2, bool pos_sig = false);
 
+/** Create a spinor metric tensor with specified indices. The indices must be
+ *  of class spinidx or a subclass and have a dimension of 2. The spinor
+ *  metric is an antisymmetric tensor with a matrix representation of
+ *  [[ [[ 0, 1 ]], [[ -1, 0 ]] ]].
+ *
+ *  @param i1 First index
+ *  @param i2 Second index
+ *  @return newly constructed spinor metric tensor */
+ex spinor_metric(const ex & i1, const ex & i2);
+
 /** Create an epsilon tensor in a Euclidean space with two indices. The
  *  indices must be of class idx or a subclass, and have a dimension of 2.
  *
@@ -183,18 +213,6 @@ ex epsilon_tensor(const ex & i1, const ex & i2, const ex & i3);
  *  @return newly constructed epsilon tensor */
 ex lorentz_eps(const ex & i1, const ex & i2, const ex & i3, const ex & i4, bool pos_sig = false);
 
-/** Create an epsilon tensor in a 4-dimensional projection of a D-dimensional
- *  Minkowski space. It vanishes whenever one of the indices is not in the
- *  set {0, 1, 2, 3}.
- *
- *  @param i1 First index
- *  @param i2 Second index
- *  @param i3 Third index
- *  @param i4 Fourth index
- *  @param pos_sig Whether the signature of the metric is positive
- *  @return newly constructed epsilon tensor */
-ex eps0123(const ex & i1, const ex & i2, const ex & i3, const ex & i4, bool pos_sig = false);
-
 } // namespace GiNaC
 
 #endif // ndef __GINAC_TENSOR_H__