Re: Solve question
- To: mathgroup at smc.vnet.net
- Subject: [mg57470] Re: [mg57457] Solve question
- From: "David Park" <djmp at earthlink.net>
- Date: Sun, 29 May 2005 01:03:28 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
L.W.,
Here is an example.
eqn = a x + b == c;
xsol = Solve[eqn, x]
{{x -> (-b + c)/a}}
Notice that Mathematica returned a List within a List. That is because there
may be more than one solution, and for multiple equations there may be more
than one variable in each solution. Generally we will want to extract a
specific solution by taking a specific part of xsol.
Let's create an x function that depends on the a,b,c parameters. We do that
by using Replace denoted by "/.". We want only the solution in the inner
bracket so we use the following:
x[a_, b_, c_] = x /. Part[xsol, 1]
(-b + c)/a
which we can now use.
x[p, q, 3]
(3 - q)/p
David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/
From: Sterritt, Lanny [mailto:lanny.sterritt at lmco.com]
To: mathgroup at smc.vnet.net
When the Solve command is used to obtain the value of a variable in an
equation, something like {x -> value} is returned. How does one get
Mathematica to automatically apply this value to following expressions in
a notebook?
L.W.Sterritt