From: Richard Kreckel <kreckel@ginac.de>
Date: Tue, 24 Nov 2015 10:14:51 +0000 (+0100)
Subject: mul::can_make_flat(): Finish ancient unfinished code.
X-Git-Tag: release_1-7-0~7^2~52
X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?a=commitdiff_plain;h=26e2662e;p=ginac.git

mul::can_make_flat(): Finish ancient unfinished code.

This makes mul(expairseq({a*b,2},{b})) construct the canonical
mul(expairseq({a,3},{b,2})). Normally, such term rewriting is done
by the .eval() methods, but this is not done when a plain object of
a class derived from basic is constructed.
---

diff --git a/ginac/mul.cpp b/ginac/mul.cpp
index f8ddd9b2..c899ee11 100644
--- a/ginac/mul.cpp
+++ b/ginac/mul.cpp
@@ -1047,10 +1047,9 @@ void mul::combine_overall_coeff(const ex & c1, const ex & c2)
 bool mul::can_make_flat(const expair & p) const
 {
 	GINAC_ASSERT(is_exactly_a<numeric>(p.coeff));
-	// this assertion will probably fail somewhere
-	// it would require a more careful make_flat, obeying the power laws
-	// probably should return true only if p.coeff is integer
-	return ex_to<numeric>(p.coeff).is_equal(*_num1_p);
+
+	// (x*y)^c == x^c*y^c  if c ∈ ℤ
+	return p.coeff.info(info_flags::integer);
 }
 
 bool mul::can_be_further_expanded(const ex & e)