MathGroup Archive: October 2011 [00319]

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Bug in Series with NonCommutativeProduct?

To: mathgroup at smc.vnet.net
Subject: [mg122096] Bug in Series with NonCommutativeProduct?
From: D J G C <dundjoh at googlemail.com>
Date: Thu, 13 Oct 2011 03:48:58 -0400 (EDT)
Delivered-to: l-mathgroup@mail-archive0.wolfram.com

> Series[(A h) ** (B h), {h, 0, 2}]

... + A B  h^2+O[h]^3

The problem is the appearance of a commutative product A B. It should
instead be A ** B

However applying the D gives the correct answer:

> D[(A h ) ** (B h), {h, 2}]

0**(B h)+2 A**B+(A h)**0

Follow-Ups:
- Re: Bug in Series with NonCommutativeProduct?
  - From: Daniel Lichtblau <danl@wolfram.com>

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