Re: using predefined expressions in functions [newbie question]

*To*: mathgroup at smc.vnet.net*Subject*: [mg100219] Re: using predefined expressions in functions [newbie question]*From*: Alexei Boulbitch <Alexei.Boulbitch at iee.lu>*Date*: Thu, 28 May 2009 06:49:51 -0400 (EDT)

Hi, ChangMo, Try to determine the function explicitly in terms of its arguments like one of the following: f1[R1_, R2_] := R1.R2; In[17]:= f1[{1, 2, 3}, {4, 5, 6}] Out[17]= 32 or otherwise, f2[x1_, y1_, z1_, x2_, y2_, z2_] := x1*x2 + y1*y2 + z1*z2; In[25]:= f[1, 2, 3, 4, 5, 6] Out[25]= 32 or like this: In[35]:= f[x1_, y1_, z1_, x2_, y2_, z2_] := {x1, y1, z1}.{x2, y2, z2}; f[1, 2, 3, 4, 5, 6] Out[36]= 32 Hi, I've been trying to write a function using some predefined expressions, but the function assignment seems to understand the symbols in the expressions as literals. eg., Needs["VectorAnalysis`"] R1 := {x1,y1,z1} R2 := {x2,y2,z2} f[x1_,y1_,z1_,x2_,y2_,z2_] := R1 . R2 f[1,2,3,4,5,6] gives the output x1 x2 + y1 y2 + z1 z2 instead of 32 ( = 1*4 + 2*5 + 3*6 ) Can anyone help me with this? Thanks for your attention. -ChangMo -- Alexei Boulbitch, Dr., habil. Senior Scientist IEE S.A. ZAE Weiergewan 11, rue Edmond Reuter L-5326 Contern Luxembourg Phone: +352 2454 2566 Fax: +352 2454 3566 Website: www.iee.lu This e-mail may contain trade secrets or privileged, undisclosed or otherwise confidential information. If you are not the intended recipient and have received this e-mail in error, you are hereby notified that any review, copying or distribution of it is strictly prohibited. Please inform us immediately and destroy the original transmittal from your system. Thank you for your co-operation.