X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Ftensor.cpp;h=d16bbfce4b7949b85359f926767673c5f66c839f;hp=ed6ad9dc4fbe373ac590d40b6ab48e64d424cbf2;hb=43e0a8f5ca5e1c48cef5daaf014acdbca4e44568;hpb=9c91319253425e66f9b6feb9e7036f841bc55e84

diff --git a/ginac/tensor.cpp b/ginac/tensor.cpp
index ed6ad9dc..d16bbfce 100644
--- a/ginac/tensor.cpp
+++ b/ginac/tensor.cpp
@@ -27,7 +27,9 @@
 #include "idx.h"
 #include "indexed.h"
 #include "relational.h"
+#include "lst.h"
 #include "numeric.h"
+#include "print.h"
 #include "archive.h"
 #include "utils.h"
 #include "debugmsg.h"
@@ -179,6 +181,15 @@ ex tensdelta::eval_indexed(const basic & i) const
 	if (is_dummy_pair(i1, i2))
 		return i1.get_dim();
 
+	// Numeric evaluation
+	if (static_cast<const indexed &>(i).all_index_values_are(info_flags::integer)) {
+		int n1 = ex_to_numeric(i1.get_value()).to_int(), n2 = ex_to_numeric(i2.get_value()).to_int();
+		if (n1 == n2)
+			return _ex1();
+		else
+			return _ex0();
+	}
+
 	// No further simplifications
 	return i.hold();
 }
@@ -324,7 +335,7 @@ bool tensmetric::contract_with(exvector::iterator self, exvector::iterator other
 
 	// If contracting with the delta tensor, let the delta do it
 	// (don't raise/lower delta indices)
-	if (is_ex_exactly_of_type(other->op(0), tensdelta))
+	if (is_ex_of_type(other->op(0), tensdelta))
 		return false;
 
 	// Try to contract first index
@@ -429,4 +440,16 @@ ex lorentz_eps(const ex & i1, const ex & i2, const ex & i3, const ex & i4, bool
 	return indexed(tensepsilon(true, pos_sig), indexed::antisymmetric, i1, i2, i3, i4);
 }
 
+ex eps0123(const ex & i1, const ex & i2, const ex & i3, const ex & i4, bool pos_sig)
+{
+	if (!is_ex_of_type(i1, varidx) || !is_ex_of_type(i2, varidx) || !is_ex_of_type(i3, varidx) || !is_ex_of_type(i4, varidx))
+		throw(std::invalid_argument("indices of epsilon tensor must be of type varidx"));
+
+	ex dim = ex_to_idx(i1).get_dim();
+	if (dim.is_equal(4))
+		return lorentz_eps(i1, i2, i3, i4, pos_sig);
+	else
+		return indexed(tensepsilon(true, pos_sig), indexed::antisymmetric, i1, i2, i3, i4);
+}
+
 } // namespace GiNaC