[Date Index]
[Thread Index]
[Author Index]
Re: Modifying equations
*To*: mathgroup at smc.vnet.net
*Subject*: [mg59171] Re: [mg59135] Modifying equations
*From*: "David Park" <djmp at earthlink.net>
*Date*: Sun, 31 Jul 2005 01:30:43 -0400 (EDT)
*Sender*: owner-wri-mathgroup at wolfram.com
Kalle,
One method is to use the Inner command.
eqn1 = a == b;
eqn2 = c == d;
Inner[Plus, eqn1, eqn2, Equal]
a + c == b + d
In the following command we divide 3 times eqn1 by k times eqn2.
Inner[3#1/(k#2) &, eqn1, eqn2, Equal]
(3*a)/(c*k) == (3*b)/(d*k)
Here are two other equations.
eqn1 = a x + b == c;
eqn2 = b y + d == f;
In the following we give an annotated step by step calculation of x + y.
(Copy the code into a Mathematica notebook and evaluate.)
Print["Solving eqn1 for x"]
# - b & /@ eqn1
xeqn = #/a & /@ %
Print["Solving eqn2 for y"]
# - d & /@ eqn2
yeqn = #/b & /@ %
Print["Calculating x + y"]
Inner[Plus, xeqn, yeqn, Equal]
You may wish to look at the StepByStepEquations notebook on the Mathematica
page of my web site below.
David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/
From: Kalle Rutanen [mailto:kalle_rutanen at nospam.hotmail.com]
To: mathgroup at smc.vnet.net
Hello
My intention is to write a mathematical paper which derives results step by
step. So here is my first question:
Given the equations
eqn1 = a == b
eqn2 = c == d
How can I combine these to form (for example)
a + c == b + d ?
I tried the obvious eqn1 + eqn2, but that does not seem to work...
Second question:
Given this:
Sum[a_i, {i, 0, n}] + Sum[b_i, {i, 0, n}]
How can I make Mathematica combine the sums giving:
Sum[a_i + b_i, {i, 0, n}] ?
Thanks.
Prev by Date:
**Re: Modifying equations**
Next by Date:
**Re: FullSimplify again ...**
Previous by thread:
**Re: Modifying equations**
Next by thread:
**Mathematica's CPU utilization**
| |