X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Ftensor.h;h=e30a91a4dcf41ec84070f7ceeb0fca6b5f9fe949;hp=7396aca177ee38b36905b94038eed109bae18b67;hb=c4c7b40ea71dd20ecc8942f9cab50c4bb9766624;hpb=06eb6b761f4b9d9eed4decd8ed50d94b40b94a0e;ds=sidebyside

diff --git a/ginac/tensor.h b/ginac/tensor.h
index 7396aca1..e30a91a4 100644
--- a/ginac/tensor.h
+++ b/ginac/tensor.h
@@ -39,7 +39,7 @@ class tensor : public basic
 protected:
 	tensor(unsigned 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; }
 };
@@ -51,7 +51,7 @@ 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 +66,7 @@ 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 +86,7 @@ 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 +97,22 @@ 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 +124,11 @@ 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:
@@ -121,6 +138,9 @@ private:
 
 
 // utility functions
+
+/** Return the tensor object handled by an ex.  Deprecated: use ex_to<tensor>().
+ *  This is unsafe: you need to check the type first. */
 inline const tensor &ex_to_tensor(const ex &e)
 {
 	return static_cast<const tensor &>(*e.bp);
@@ -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.
  *
@@ -183,6 +213,18 @@ 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__