Re: Series expansion question

*To*: mathgroup at smc.vnet.net*Subject*: [mg122705] Re: Series expansion question*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Mon, 7 Nov 2011 05:51:29 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

On 11/6/11 at 5:56 AM, recif at yahoo.com (Recif) wrote: >I defined a function: gts[x_, y_] := Normal[Series[g[x, y], {x, x0, >1}, {y, y0, 1}]] >and when I use it with 'a' and 'b' undefined, I get the value I >expect: >However when I assign values to a and b: >a = x0 + z >b = y0 + z >gts[a,b] gives me an error How about: In[2]:= gts[x_, y_] := Block[{a, b}, Normal[Series[g[a, b], {a, x0, 1}, {b, y0, 1}]] /. {a -> x, b -> y}] In[3]:= gts[x + x0, y + y0] Out[3]= y*(x*Derivative[1, 1][g][x0, y0] + Derivative[0, 1][g][x0, y0]) + x*Derivative[1, 0][g][x0, y0] + g[x0, y0]