Groups > comp.soft-sys.math.mathematica > #3190

How to find one expression in terms of another expression?

From	Jacare Omoplata <walkeystalkey@gmail.com>
Newsgroups	comp.soft-sys.math.mathematica
Subject	How to find one expression in terms of another expression?
Date	2011-06-19 23:29 +0000
Organization	Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Message-ID	<itm0of$143$1@smc.vnet.net> (permalink)

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I want to find dT in terms of dt. They are given below.



In[1]:= Element[{x1, x2, t1, t2, u, c}, Reals]

Out[1]= (x1 | x2 | t1 | t2 | u | c) \[Element] Reals

In[3]:= T1 = (t1 - ((u x1)/c^2))/Sqrt[1 - (u^2/c^2)]

Out[3]= (t1 - (u x1)/c^2)/Sqrt[1 - u^2/c^2]

In[4]:= T2 = (t2 - ((u x2)/c^2))/Sqrt[1 - (u^2/c^2)]

Out[4]= (t2 - (u x2)/c^2)/Sqrt[1 - u^2/c^2]

In[5]:= dT = T2 - T1

Out[5]= -((t1 - (u x1)/c^2)/Sqrt[1 - u^2/c^2]) + (
 t2 - (u x2)/c^2)/Sqrt[1 - u^2/c^2]

In[6]:= dt = t2 - t1

Out[6]= -t1 + t2


If I knew that dT can be written in terms of dt in the form,
dT = a dt + b,
Can I use Mathematica to find a and b?

I tried using  Solve[dT == a dt + b, dt], but that gives an error.

If I didn't know that dT can be expressed this way, can I still
express it in terms of dt ?

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Thread

How to find one expression in terms of another expression? Jacare Omoplata <walkeystalkey@gmail.com> - 2011-06-19 23:29 +0000
  Re: How to find one expression in terms of another expression? Ray Koopman <koopman@sfu.ca> - 2011-06-20 23:37 +0000
    Re: How to find one expression in terms of another expression? Jacare Omoplata <walkeystalkey@gmail.com> - 2011-06-21 11:18 +0000
  Multiple use of Set on lists Jonathan Frazer <J.Frazer@sussex.ac.uk> - 2011-06-20 23:38 +0000
    Re: Multiple use of Set on lists Oleksandr Rasputinov <oleksandr_rasputinov@hmamail.com> - 2011-06-21 11:17 +0000
  Re: Multiple use of Set on lists Leonid Shifrin <lshifr@gmail.com> - 2011-06-25 09:31 +0000

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