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MathGroup Archive 2005

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Re: display of function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg58524] Re: [mg58506] display of function
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Tue, 5 Jul 2005 06:34:16 -0400 (EDT)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

p = {p1,p2,p3};

y={y1, y2, y3};

Use the dot product

p.y

p1*y1 + p2*y2 + p3*y3

p = {.3,.4,.3};

y={10000, 20000, 30000};

p.y

20000.

For your function to work, you would need to use Part rather than Subscript 
and define n (i.e., provide a numerical value for the index upper limit).

u[y_]:=Sum[p[[i]]*y[[i]],{i,1,Length[y]}];

u[y]

20000.


Bob Hanlon

> 
> From: "Bosch, Darrell" <bosch at vt.edu>
To: mathgroup at smc.vnet.net
> Date: 2005/07/05 Tue AM 01:57:45 EDT
> Subject: [mg58524] [mg58506] display of function
> 
> 
> Dear Math Group:
> 
>             The first equation below shows a function for u(y) which is
> the sum of the products of pi times yi.  In the following steps, I
> assign values of p and y.   How can I get Mathematica to display the
> numerical value of u for the given p and y values?  When I insert the
> u[y] command, I just get a repeat of the equation I have entered.
> Thanks for your suggestions.  This group is a great help.  Darrell
> 
> 
> 
> u[y_] := Sum[Subscript[p, i]*Subscript[y, i],
> 
>    {i, 1, n}]
> 
> 
> 
> p = {.3,.4,.3}
> 
> 
> 
> y={10000, 20000, 30000}
> 
> 
> 


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