fixed a bug where quo() would call vector::reserve() with a negative argument

[ginac.git] / ginac / normal.cpp

diff --git a/ginac/normal.cpp b/ginac/normal.cpp
index ee27868165e02e148960407369b8d18da282f180..4b490ed0e9824d301cb979fc830433b98aa22019 100644 (file)
--- a/ginac/normal.cpp
+++ b/ginac/normal.cpp
@@ -381,7 +381,7 @@ ex quo(const ex &a, const ex &b, const symbol &x, bool check_args)
        int rdeg = r.degree(x);
        ex blcoeff = b.expand().coeff(x, bdeg);
        bool blcoeff_is_numeric = is_ex_exactly_of_type(blcoeff, numeric);
-       exvector v; v.reserve(rdeg - bdeg + 1);
+       exvector v; v.reserve(std::max(rdeg - bdeg + 1, 0));
        while (rdeg >= bdeg) {
                ex term, rcoeff = r.coeff(x, rdeg);
                if (blcoeff_is_numeric)
@@ -581,14 +581,15 @@ ex sprem(const ex &a, const ex &b, const symbol &x, bool check_args)
  *  @param check_args  check whether a and b are polynomials with rational
  *         coefficients (defaults to "true")
  *  @return "true" when exact division succeeds (quotient returned in q),
- *          "false" otherwise */
+ *          "false" otherwise (q left untouched) */
 bool divide(const ex &a, const ex &b, ex &q, bool check_args)
 {
-       q = _ex0;
        if (b.is_zero())
                throw(std::overflow_error("divide: division by zero"));
-       if (a.is_zero())
+       if (a.is_zero()) {
+               q = _ex0;
                return true;
+       }
        if (is_ex_exactly_of_type(b, numeric)) {
                q = a / b;
                return true;
@@ -611,13 +612,15 @@ bool divide(const ex &a, const ex &b, ex &q, bool check_args)
 
        // Polynomial long division (recursive)
        ex r = a.expand();
-       if (r.is_zero())
+       if (r.is_zero()) {
+               q = _ex0;
                return true;
+       }
        int bdeg = b.degree(*x);
        int rdeg = r.degree(*x);
        ex blcoeff = b.expand().coeff(*x, bdeg);
        bool blcoeff_is_numeric = is_ex_exactly_of_type(blcoeff, numeric);
-       exvector v; v.reserve(rdeg - bdeg + 1);
+       exvector v; v.reserve(std::max(rdeg - bdeg + 1, 0));
        while (rdeg >= bdeg) {
                ex term, rcoeff = r.coeff(*x, rdeg);
                if (blcoeff_is_numeric)
@@ -778,7 +781,7 @@ static bool divide_in_z(const ex &a, const ex &b, ex &q, sym_desc_vec::const_ite
        int rdeg = adeg;
        ex eb = b.expand();
        ex blcoeff = eb.coeff(*x, bdeg);
-       exvector v; v.reserve(rdeg - bdeg + 1);
+       exvector v; v.reserve(std::max(rdeg - bdeg + 1, 0));
        while (rdeg >= bdeg) {
                ex term, rcoeff = r.coeff(*x, rdeg);
                if (!divide_in_z(rcoeff, blcoeff, term, var+1))