A stupid but practical question

• To: mathgroup at smc.vnet.net
• Subject: [mg25825] A stupid but practical question
• From: Chen Jisheng <chenjs at iopp.ccnu.edu.cn>
• Date: Sat, 28 Oct 2000 01:41:17 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

``` Dear Sir,

As a new user, I need to solve the following problem.  For example, I
have a complicated equation f(x,T,m)==0 of T, and x, for a range of T
(e.g., T=10-200). The m is a parameter, which can be inputed with hand.

For a given value of T and m, I can find a solution x of above equation
with "commands". So on, with hand input the values of T in a range, I can
find all the solutions for a given parameter m. With a pen at hand, I can
write down all the groups of T and x with a concrete value of m.

The final aim is to draw out the curve x-T with given m. Reinputing
the data of groups (x,T) such as written down above, I can draw out the
curve.

But I think above method is not a intelligent solution. With programming,
I think mathematics can sovle it more efficiently.

With a given value of m, here is my question:

1) How to do the programming? Although I try it some times with the
Do-loop, but the intermediate value of x can not be displayed with a group
of T in one loop.
2) With the programming, I hope to control a table such as t={{x,T}}. In
every loop, I find only the value of the first group (x,T) can be appended
to such this table. In the loop, how can I append the new value of T and x
to this table?
3) Another way, if I have a data file such as: d.dat
"T x"
10 200
15 210
20 211
...

In the loop of programming, how can I open this data file, add new data
and close this data file?

You may think it is a stupid question although it is very practical.
Although I was a student with high score in "BASIC","FORTRAN" and even
"C", I still find it difficult to solve it clever because I don't know
exactly how to operate the data file in the (loop) programming, of course
with mathematics.

Looking forward to receiving the reply.

J.-S CHen,
Institute of Particle Physics,
Hua-Zhong Normal University,
Wuhan 430079,China

```

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