Re: Do loops in Mathematica
- To: mathgroup at smc.vnet.net
- Subject: [mg55177] Re: Do loops in Mathematica
- From: Jon Harrop <usenet at jdh30.plus.com>
- Date: Wed, 16 Mar 2005 05:35:53 -0500 (EST)
- References: <d15s6o$9l2$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
dumb_founded wrote:
> I am having trouble setting up Do loops in Mathematica. Even when I
> put in a return statement, I get no output. Below is a concrete
> example of code I am putting in:
>
> Do[{p = Solve[x^2 + 3*x + 1 == 0, x], Return[2*p]}, {i, 1}]
>
> I get nothing out of it.
Yes, by using "Do" you are asking Mathematica to repeatedly do something and
_not_ return the answer. You want "Table" instead of "Do":
In[1]:= Table[{p = Solve[x^2 + 3*x + 1 == 0, x], Return[2*p]}, {i, 1}]
-3 - Sqrt[5] -3 + Sqrt[5]
Out[1]= {{{{x -> ------------}, {x -> ------------}},
2 2
-3 - Sqrt[5] -3 + Sqrt[5]
> Return[{{2 (x -> ------------)}, {2 (x -> ------------)}}]}}
2 2
In computer science terminology, it could be said that "Do" is an imperative
construct and "Table" is a functional construct.
> I am having a headache figuring out this simple chore. Mathematica
> simply refuses to behave.
Mathematica is doing precisely what you ask it to do.
--
Dr Jon D Harrop, Flying Frog Consultancy
http://www.ffconsultancy.com