- fixed bug in normal(): normal(x^a) became (x^(-a))^(-1)

[ginac.git] / ginac / inifcns.cpp

diff --git a/ginac/inifcns.cpp b/ginac/inifcns.cpp
index bc401f47266272789b371d9bdced87464ddc3ba7..e9e2cad1421b0bbcbccd985d487f61994d58d62a 100644 (file)
--- a/ginac/inifcns.cpp
+++ b/ginac/inifcns.cpp
@@ -166,9 +166,50 @@ static ex Order_series(const ex & x, const symbol & s, const ex & point, int ord
        return pseries(s, point, new_seq);
 }
 
+// Differentiation is handled in function::derivative because of its special requirements
+
 REGISTER_FUNCTION(Order, eval_func(Order_eval).
                          series_func(Order_series));
 
+//////////
+// Inert differentiation
+//////////
+
+static ex Diff_eval(const ex & f, const ex & x)
+{
+       return Diff(f, x).hold();
+}
+
+static ex Diff_deriv(const ex & f, const ex & x, unsigned deriv_param)
+{
+       GINAC_ASSERT(deriv_param == 0 || deriv_param == 1);
+       if (deriv_param == 1)
+               return Diff(Diff(f, x), x);
+       else
+               return _ex0();
+}
+
+REGISTER_FUNCTION(Diff, eval_func(Diff_eval).
+                        derivative_func(Diff_deriv));
+
+//////////
+// Inert partial differentiation operator
+//////////
+
+static ex Derivative_eval(const ex & f, const ex & n)
+{
+       if (is_ex_exactly_of_type(n, numeric) && ex_to_numeric(n).is_nonneg_integer()) {
+               unsigned i = ex_to_numeric(n).to_int();
+               if (is_ex_exactly_of_type(f, function)) {
+                       if (i < f.nops() && is_ex_exactly_of_type(f.op(i), symbol))
+                               return Diff(f, f.op(i));
+               }
+       }
+       return Derivative(f, n).hold();
+}
+
+REGISTER_FUNCTION(Derivative, eval_func(Derivative_eval));
+
 //////////
 // Solve linear system
 //////////
@@ -212,10 +253,10 @@ ex lsolve(const ex &eqns, const ex &symbols)
     matrix vars(symbols.nops(),1);
     
     for (unsigned r=0; r<eqns.nops(); r++) {
-        ex eq=eqns.op(r).op(0)-eqns.op(r).op(1); // lhs-rhs==0
-        ex linpart=eq;
+        ex eq = eqns.op(r).op(0)-eqns.op(r).op(1); // lhs-rhs==0
+        ex linpart = eq;
         for (unsigned c=0; c<symbols.nops(); c++) {
-            ex co=eq.coeff(ex_to_symbol(symbols.op(c)),1);
+            ex co = eq.coeff(ex_to_symbol(symbols.op(c)),1);
             linpart -= co*symbols.op(c);
             sys.set(r,c,co);
         }
@@ -226,18 +267,16 @@ ex lsolve(const ex &eqns, const ex &symbols)
     // test if system is linear and fill vars matrix
     for (unsigned i=0; i<symbols.nops(); i++) {
         vars.set(i,0,symbols.op(i));
-        if (sys.has(symbols.op(i))) {
+        if (sys.has(symbols.op(i)))
             throw(std::logic_error("lsolve: system is not linear"));
-        }
-        if (rhs.has(symbols.op(i))) {
+        if (rhs.has(symbols.op(i)))
             throw(std::logic_error("lsolve: system is not linear"));
-        }
     }
     
     //matrix solution=sys.solve(rhs);
     matrix solution;
     try {
-        solution=sys.fraction_free_elim(vars,rhs);
+        solution = sys.fraction_free_elim(vars,rhs);
     } catch (const runtime_error & e) {
         // probably singular matrix (or other error)
         // return empty solution list