MathGroup Archive 1997

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RE: Re: Assigning solutions fou

  • To: mathgroup at smc.vnet.net
  • Subject: [mg9490] RE: [mg9450] Re: Assigning solutions fou
  • From: Ersek_Ted%PAX1A at mr.nawcad.navy.mil
  • Date: Sat, 8 Nov 1997 23:04:23 -0500
  • Sender: owner-wri-mathgroup at wolfram.com

Hein Hundal replied to a question about how to convert a list of Rules
from  FindRoot to a list of numbers.
Hein said:
|
| Try
|
| sols=FindRoot[{x == y, x + y == 2}, {x, 0}, {y, 0}] Set @@#& /@ sols |
|

Are you sure?  It doesn't work for me unless I include a semi-colon as 
follows:


In[1]:=  sols=FindRoot[{x == y, x + y == 2}, {x, 0}, {y, 0}] ;Set @@#&
/@  sols

Out[1]=  {1.,1.}


I find this sort of code very cryptic, and I think it's a sure fire way
to  turn off beginners.
Besides that it goes about the task in a round about way. Something like
the following is more direct and more readable.


In[2]:=  solution=FindRoot[{x == y, x + y == 2}, {x, 0}, {y, 0}]

Out[2]=  {1.\[Rule]1.,1.\[Rule]1.}

In[3]:=  {x,y}/.solution

Out[3]=  {1.,1.}


Note:  I didn't put a semi-colon after FindRoot[.......] so a beginner
will  know what the next line is working on. Now if the user wanted to
assign values to {x,y} they could use the  following.

In[4]:=  {x,y}={x,y}/.solution

Out[4]=  {1.,1.}

          Ted Ersek
          ersek_ted%pax1a at mr.nawcad.navy.mil



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