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Re: problem with Coefficient

• To: mathgroup@smc.vnet.net
• Subject: [mg12135] Re: [mg12041] problem with Coefficient
• From: Sean Ross <seanross@worldnet.att.net>
• Date: Mon, 27 Apr 1998 01:46:18 -0400
• References: <199804240552.BAA13217@smc.vnet.net.>

vonessen@selway.umt.edu wrote:
> 
> The Mathematica function Coefficient seemingly does not always work as
> it should:
> 
> In[1]:=Coefficient[x^2 y^2,x^2 y^2]
> Out[1]=1
> In[2]:=Coefficient[x1^2 x2^2,x1^2 x2^2] Out[2]=0
> 
> The first computation is correct, the second not.  I made this
> computation on several computers using Mathematica 3.0 under Windows
> 95.

No help, but some other input to the discussion:

						   returns
Coefficient[x^2  y^2,x^2  y^2]     			1 Coefficient[x1^2  y1^2,x1^2 
y1^2]			1 Coefficient[x1^2  y2^2,x1^2  y2^2]			1 Coefficient[x1^2 
x2^2,x1^2  x2^2]			0 Coefficient[(x1)^2 (x2)^2,Evaluate[(x1)^2 
(x2)^2]]	0 Coefficient[x2^2  x3^2,x2^2  x3^2]			0 Coefficient[fred2^2 
fred3^2,fred2^2  fred3^2]		0 Coefficient[polly2^2  fred3^2,polly2^2 
fred3^2]	0 Coefficient[p^2  f^2,p^2  f^2]				1
Coefficient[Evaluate[x1^2  x2^2/.{x1->x,x2->y}],
  Evaluate[x1^2  x2^2/.{x1->x,x2->y}]]			1

It seems like it cannot correctly handle similar symbols or long symbol
names and works best with single letters and no numbers.  This is a
strange limitation.  I wonder if this would pass technical supports
definition of a bug?  If it is not a bug, but a "feature", I would be
very interested to know the explanation.

• References:
  • problem with Coefficient
    • From: vonessen@selway.umt.edu