- simplify_indexed() simplifies c*(M).i.j -> (M').i.j (c: numeric, M: matrix)

[ginac.git] / ginac / indexed.cpp

diff --git a/ginac/indexed.cpp b/ginac/indexed.cpp
index fb34df9502a861c35f32cd739f01c4410e605ed6..86fe6115d9b8863819c44e3a393d9c99cd0b01d4 100644 (file)
--- a/ginac/indexed.cpp
+++ b/ginac/indexed.cpp
@@ -330,6 +330,20 @@ ex indexed::eval(int level) const
        if (level > 1)
                return indexed(symmetry, evalchildren(level));
 
+       const ex &base = seq[0];
+
+       // If the base object is 0, the whole object is 0
+       if (base.is_zero())
+               return _ex0();
+
+       // If the base object is a product, pull out the numeric factor
+       if (is_ex_exactly_of_type(base, mul) && is_ex_exactly_of_type(base.op(base.nops() - 1), numeric)) {
+               exvector v = seq;
+               ex f = ex_to_numeric(base.op(base.nops() - 1));
+               v[0] = seq[0] / f;
+               return f * thisexprseq(v);
+       }
+
        // Canonicalize indices according to the symmetry properties
        if (seq.size() > 2 && (symmetry != unknown && symmetry != mixed)) {
                exvector v = seq;
@@ -343,7 +357,7 @@ ex indexed::eval(int level) const
        }
 
        // Let the class of the base object perform additional evaluations
-       return op(0).bp->eval_indexed(*this);
+       return base.bp->eval_indexed(*this);
 }
 
 ex indexed::thisexprseq(const exvector & v) const
@@ -665,13 +679,21 @@ try_again:
        }
        find_free_and_dummy(un.begin(), un.end(), free_indices, dummy_indices);
 
+       ex r;
        if (something_changed) {
                if (non_commutative)
-                       return ncmul(v);
+                       r = ncmul(v);
                else
-                       return mul(v);
+                       r = mul(v);
        } else
-               return e;
+               r = e;
+
+       // Product of indexed object with a scalar?
+       if (is_ex_exactly_of_type(r, mul) && r.nops() == 2
+        && is_ex_exactly_of_type(r.op(1), numeric) && is_ex_of_type(r.op(0), indexed))
+               return r.op(0).op(0).bp->scalar_mul_indexed(r.op(0), ex_to_numeric(r.op(1)));
+       else
+               return r;
 }
 
 /** Simplify indexed expression, return list of free indices. */
@@ -691,15 +713,17 @@ ex simplify_indexed(const ex & e, exvector & free_indices, const scalar_products
        // Simplification of sum = sum of simplifications, check consistency of
        // free indices in each term
        if (is_ex_exactly_of_type(e_expanded, add)) {
-               ex sum = _ex0();
+               ex sum = simplify_indexed(e_expanded.op(0), free_indices, sp);
 
-               for (unsigned i=0; i<e_expanded.nops(); i++) {
+               for (unsigned i=1; i<e_expanded.nops(); i++) {
                        exvector free_indices_of_term;
-                       sum += simplify_indexed(e_expanded.op(i), free_indices_of_term, sp);
-                       if (i == 0)
-                               free_indices = free_indices_of_term;
-                       else if (!indices_consistent(free_indices, free_indices_of_term))
+                       ex term = simplify_indexed(e_expanded.op(i), free_indices_of_term, sp);
+                       if (!indices_consistent(free_indices, free_indices_of_term))
                                throw (std::runtime_error("simplify_indexed: inconsistent indices in sum"));
+                       if (is_ex_of_type(sum, indexed) && is_ex_of_type(term, indexed))
+                               sum = sum.op(0).bp->add_indexed(sum, term);
+                       else
+                               sum += term;
                }
 
                return sum;