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Re: How to remove curly brackets and arrow symbols from a list.
*To*: mathgroup at smc.vnet.net
*Subject*: [mg58209] Re: How to remove curly brackets and arrow symbols from a list.
*From*: David Bailey <dave at Remove_Thisdbailey.co.uk>
*Date*: Thu, 23 Jun 2005 05:33:45 -0400 (EDT)
*References*: <d9av83$10a$1@smc.vnet.net>
*Sender*: owner-wri-mathgroup at wolfram.com
T. K. Ghosh wrote:
> Hi Math Guru,
>
> I will be very happy if you could help me to solve the following problem.
> The simplified version of my problem is the following.
> I have a quadratic equation with a parameter, say "p".
>
> Define the function:
> f[x_] := A*X^2 + B*X*p + D with A, B and D are given.
> "p" is a parameter.
> I solve this equation for a given p:
> w = Solve[f[x]] == 0, X].
> Now I want to make a Table for the solutions of this
> quadratic equation for different values of "p".
> So I write,
> Table[{p,sol},{p,0,10,1}.
> I will get a table which will look like,
> 0 {w -> a} {w -> -a}
> 1 {w -> b} {w -> -b}
> 2 {w -> c} {w -> -c}
> and so on.........
>
> How can I remove the curly brackets and the arrow symbol
> from the TableForm? I would like to plot the 1st column
> vs. 2nd or 3rd column. I must remove those brackets.
> and I wish to get the following form:
> 0 a -a
> 1 b -b
> 2 c -c
>
>
> Hope this can be done easily which I am not aware.
> Any suggestion/solution to this problem is most welcome.
> Thanking you in advance.
> TKG.
>
Hello,
First please note that 'x' and 'X' are distinct variables. If you give a
quadratic equation to Solve, you will get back a list of TWO solutions -
because that is the nature of quadratic equations! If you don't care
which solution you want, you could just select one of these:
w=Solve[f[x] == 0, x][[1]]
At this point w will have a value something like {x->answer}. This is
extremely useful in general because you can use it to substitute the
value of x into any expression involving x. In your case you want:
w= x/.Solve[f[x] == 0, x][[1]]
Now w is the answer you want (as a function of p) and you can use it to
build your table without any curly brackets!
If I were you I would invest some time reading that heavy brick that
came with your Mathematica disks - or even go on a course - once you
learn a little more you will see how all this clicks together.
David Bailey
http://www.dbaileyconsultancy.co.uk
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