metric tensors now silently replace their indices' dimensions with their

[ginac.git] / ginac / tensor.cpp

diff --git a/ginac/tensor.cpp b/ginac/tensor.cpp
index 08c2ecc65ea253fe70284f110f403a526392c171..0c36a68002423d712f4d8afa5ec903716ffba7e7 100644 (file)
--- a/ginac/tensor.cpp
+++ b/ginac/tensor.cpp
@@ -213,6 +213,13 @@ ex tensmetric::eval_indexed(const basic & i) const
        const varidx & i1 = ex_to<varidx>(i.op(1));
        const varidx & i2 = ex_to<varidx>(i.op(2));
 
+       // The dimension of the indices must be equal, otherwise we use the minimal
+       // dimension
+       if (!i1.get_dim().is_equal(i2.get_dim())) {
+               ex min_dim = i1.minimal_dim(i2);
+               return i.subs(lst(i1 == i1.replace_dim(min_dim), i2 == i2.replace_dim(min_dim)));
+       }
+
        // A metric tensor with one covariant and one contravariant index gets
        // replaced by a delta tensor
        if (i1.is_covariant() != i2.is_covariant())
@@ -519,9 +526,6 @@ ex metric_tensor(const ex & i1, const ex & i2)
 {
        if (!is_ex_of_type(i1, varidx) || !is_ex_of_type(i2, varidx))
                throw(std::invalid_argument("indices of metric tensor must be of type varidx"));
-       ex dim = ex_to<idx>(i1).get_dim();
-       if (!dim.is_equal(ex_to<idx>(i2).get_dim()))
-               throw(std::invalid_argument("all indices of metric tensor must have the same dimension"));
 
        return indexed(tensmetric(), sy_symm(), i1, i2);
 }
@@ -530,9 +534,6 @@ ex lorentz_g(const ex & i1, const ex & i2, bool pos_sig)
 {
        if (!is_ex_of_type(i1, varidx) || !is_ex_of_type(i2, varidx))
                throw(std::invalid_argument("indices of metric tensor must be of type varidx"));
-       ex dim = ex_to<idx>(i1).get_dim();
-       if (!dim.is_equal(ex_to<idx>(i2).get_dim()))
-               throw(std::invalid_argument("all indices of metric tensor must have the same dimension"));
 
        return indexed(minkmetric(pos_sig), sy_symm(), i1, i2);
 }