From: Alexei Sheplyakov Date: Mon, 17 May 2010 22:21:53 +0000 (+0200) Subject: Added degree_vector' utility function. X-Git-Tag: release_1-5-8~7 X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=commitdiff_plain;h=6201dc3c6562e0b8c174129af382fd5745de048f Added degree_vector' utility function. It's a generalization of degree(expr, var) for multivariate polynomials. --- diff --git a/ginac/polynomial/collect_vargs.cpp b/ginac/polynomial/collect_vargs.cpp index 25932687..c4368fb2 100644 --- a/ginac/polynomial/collect_vargs.cpp +++ b/ginac/polynomial/collect_vargs.cpp @@ -177,6 +177,18 @@ ex lcoeff_wrt(ex e, const exvector& x) return ec.rbegin()->second; } +exp_vector_t degree_vector(ex e, const exvector& vars) +{ + e = e.expand(); + exp_vector_t dvec(vars.size()); + for (std::size_t i = vars.size(); i-- != 0; ) { + const int deg_i = e.degree(vars[i]); + e = e.coeff(vars[i], deg_i); + dvec[i] = deg_i; + } + return dvec; +} + cln::cl_I integer_lcoeff(const ex& e, const exvector& vars) { ex_collect_t ec; diff --git a/ginac/polynomial/collect_vargs.h b/ginac/polynomial/collect_vargs.h index 44c3d72c..a927c3f5 100644 --- a/ginac/polynomial/collect_vargs.h +++ b/ginac/polynomial/collect_vargs.h @@ -28,10 +28,34 @@ #include #include // for std::pair #include +#include // std::lexicographical_compare namespace GiNaC { typedef std::vector exp_vector_t; + +static inline bool operator<(const exp_vector_t& v1, const exp_vector_t& v2) +{ + return std::lexicographical_compare(v1.rbegin(), v1.rend(), + v2.rbegin(), v2.rend()); +} + +static inline bool operator>(const exp_vector_t& v1, const exp_vector_t& v2) +{ + if (v1 == v2) + return false; + return !(v1 < v2); +} + +static inline bool zerop(const exp_vector_t& v) +{ + for (exp_vector_t::const_reverse_iterator i = v.rbegin(); i != v.rend(); ++i) { + if (*i != 0) + return false; + } + return true; +} + typedef std::vector > ex_collect_t; extern void @@ -46,6 +70,13 @@ ex_collect_to_ex(const ex_collect_t& ec, const exvector& x); */ extern ex lcoeff_wrt(ex e, const exvector& x); + +/** + * Degree vector of a leading term of a multivariate polynomial. + * (generalization of degree(expr, var)) + */ +extern exp_vector_t degree_vector(ex e, const exvector& vars); + /** * Leading coefficient c \in R (where R = Z or Z_p) of a multivariate * polynomial e \in R[x_0, \ldots, x_n]