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Series and passing a function a changing number of variables

• To: mathgroup at smc.vnet.net
• Subject: [mg106758] Series and passing a function a changing number of variables
• From: Ignacio Plazeta <Ignacio.Plazeta at speednet.es>
• Date: Sat, 23 Jan 2010 07:29:27 -0500 (EST)

Dear Friends

-- 1 -----------------------------------------------

This command works fine:

Series[ Exp[ x + 2 y^x ] , {x, 0, 2} ,  {y, 0, 2} ]

this one doesn't:

Series[ Exp[ x + 2 y^x ] ,  {{x, 0, 2}, {y, 0, 2}} ]

It returns:

"Series specification is not a list with three elements ..."

-- 2 -----------------------------------------------

I'm trying to set up this kind of function:

myTaylorExpander[ function_ , varList , startPoint_ , ord_ ]

where varList length is changing; because of the above mentioned
behavior of Series function I can't simply try something like:

numVar = Length[ varList ];

args = Table[

{ varList[[k]] , startPoint , ord}

, { k, 1 , numVar }

]

Series[ f , args ] // Normal

-- 3 -----------------------------------------------

Is there a way to get out of this by a trick to pass a functions
a changing number of variable ? Anything else fitting is welcomed too.

Warmest Regards.

Ignacio Plazeta
( Spain )

• Follow-Ups:
  • Re: Series and passing a function a changing number of
    • From: Leonid Shifrin <lshifr@gmail.com>