- pseries::power_const(): check for integer-exponent invariant.
authorRichard Kreckel <Richard.Kreckel@uni-mainz.de>
Wed, 1 Aug 2001 21:44:50 +0000 (21:44 +0000)
committerRichard Kreckel <Richard.Kreckel@uni-mainz.de>
Wed, 1 Aug 2001 21:44:50 +0000 (21:44 +0000)
- mul::series(): remove some bloat.

ginac/pseries.cpp

index 720fb9c732daef58311ac1b46d296246c2ce8288..5812982447a68816d4a5d956efc0cae8fec124e7 100644 (file)
@@ -266,7 +266,7 @@ int pseries::degree(const ex &s) const
        if (var.is_equal(s)) {
                // Return last exponent
                if (seq.size())
-                       return ex_to<numeric>((*(seq.end() - 1)).coeff).to_int();
+                       return ex_to<numeric>((seq.end()-1)->coeff).to_int();
                else
                        return 0;
        } else {
@@ -294,7 +294,7 @@ int pseries::ldegree(const ex &s) const
        if (var.is_equal(s)) {
                // Return first exponent
                if (seq.size())
-                       return ex_to<numeric>((*(seq.begin())).coeff).to_int();
+                       return ex_to<numeric>((seq.begin())->coeff).to_int();
                else
                        return 0;
        } else {
@@ -682,7 +682,6 @@ ex pseries::mul_series(const pseries &other) const
        
        // Series multiplication
        epvector new_seq;
-       
        int a_max = degree(var);
        int b_max = other.degree(var);
        int a_min = ldegree(var);
@@ -723,30 +722,25 @@ ex pseries::mul_series(const pseries &other) const
  *  @see ex::series */
 ex mul::series(const relational & r, int order, unsigned options) const
 {
-       ex acc; // Series accumulator
-       
-       // Get first term from overall_coeff
-       acc = overall_coeff.series(r, order, options);
-       
+       pseries acc; // Series accumulator
+
        // Multiply with remaining terms
-       epvector::const_iterator it = seq.begin();
-       epvector::const_iterator itend = seq.end();
-       for (; it!=itend; ++it) {
+       const epvector::const_iterator itbeg = seq.begin();
+       const epvector::const_iterator itend = seq.end();
+       for (epvector::const_iterator it=itbeg; it!=itend; ++it) {
                ex op = it->rest;
-               if (op.info(info_flags::numeric)) {
-                       // series * const (special case, faster)
-                       ex f = power(op, it->coeff);
-                       acc = ex_to<pseries>(acc).mul_const(ex_to<numeric>(f));
-                       continue;
-               } else if (!is_ex_exactly_of_type(op, pseries))
+               if (!is_ex_exactly_of_type(op, pseries))
                        op = op.series(r, order, options);
                if (!it->coeff.is_equal(_ex1()))
                        op = ex_to<pseries>(op).power_const(ex_to<numeric>(it->coeff), order);
 
                // Series multiplication
-               acc = ex_to<pseries>(acc).mul_series(ex_to<pseries>(op));
+               if (it==itbeg)
+                       acc = ex_to<pseries>(op);
+               else
+                       acc = ex_to<pseries>(acc.mul_series(ex_to<pseries>(op)));
        }
-       return acc;
+       return acc.mul_const(ex_to<numeric>(overall_coeff));
 }
 
 
@@ -778,17 +772,19 @@ ex pseries::power_const(const numeric &p, int deg) const
        // then of course x^(p*m) but the recurrence formula still holds.
        
        if (seq.empty()) {
-               // as a spacial case, handle the empty (zero) series honoring the
+               // as a special case, handle the empty (zero) series honoring the
                // usual power laws such as implemented in power::eval()
                if (p.real().is_zero())
-                       throw (std::domain_error("pseries::power_const(): pow(0,I) is undefined"));
+                       throw std::domain_error("pseries::power_const(): pow(0,I) is undefined");
                else if (p.real().is_negative())
-                       throw (pole_error("pseries::power_const(): division by zero",1));
+                       throw pole_error("pseries::power_const(): division by zero",1);
                else
                        return *this;
        }
        
-       int ldeg = ldegree(var);
+       const int ldeg = ldegree(var);
+       if (!(p*ldeg).is_integer())
+               throw std::runtime_error("pseries::power_const(): trying to assemble a Puiseux series");
        
        // Compute coefficients of the powered series
        exvector co;
@@ -807,7 +803,7 @@ ex pseries::power_const(const numeric &p, int deg) const
                }
                if (!sum.is_zero())
                        all_sums_zero = false;
-               co.push_back(sum / coeff(var, ldeg) / numeric(i));
+               co.push_back(sum / coeff(var, ldeg) / i);
        }
        
        // Construct new series (of non-zero coefficients)
@@ -815,14 +811,14 @@ ex pseries::power_const(const numeric &p, int deg) const
        bool higher_order = false;
        for (int i=0; i<deg; ++i) {
                if (!co[i].is_zero())
-                       new_seq.push_back(expair(co[i], numeric(i) + p * ldeg));
+                       new_seq.push_back(expair(co[i], p * ldeg + i));
                if (is_order_function(co[i])) {
                        higher_order = true;
                        break;
                }
        }
        if (!higher_order && !all_sums_zero)
-               new_seq.push_back(expair(Order(_ex1()), numeric(deg) + p * ldeg));
+               new_seq.push_back(expair(Order(_ex1()), p * ldeg + deg));
        return pseries(relational(var,point), new_seq);
 }