[Date Index]
[Thread Index]
[Author Index]
# RE: weird eqns
Hi Troy,
Like so many problems in Mathematica, you often need to manipulate a bit
to get the answer you want, rather than simply blindly plugging
things in. And even if you can get an answer by blindly plugging
things in, if you haven't played around with the equations with
pencil and paper you will likely get blindsided with an unexpected
(ie wrong) answer. Playing around with your equations it is clear
that they have such large exponents that it makes them rather
unstable to a direct numerical attack unless you have some idea in
advance where you are looking. If you label your constants as: alpha
38530, beta 6, gamma .987*2.303, delta 3000, and
epsilon 167 then you are really interested in the region where
the exponent of 10 is close to zero. You can find this using:
NSolve[ -(alpha + delta) + (beta + epsilon) t Ð0, t] Which
gives the solution t-> 27.9301 If you rearrange your equations you can
use FindRoot to get the more exact answer: t->27.8973
Then you easily find that the rest of the solutions are (essentially,
rounded to close rational):
b /3; c (actually c .12 x 10^(-294)); o /3
Hope that helps.
RF
-----Original Message-----
From: s2700114@nickel.laurentian.ca [SMTP:s2700114@nickel.laurentian.ca]
To: mathgroup@smc.vnet.net
Sent: Friday, January 30, 1998 3:25 AM To: mathgroup@smc.vnet.net
Subject: [mg10698] weird eqns
I have four equations ond would like mathematica to solve them using
NSolve. everytime i try this it returns with a transcendental function
error. I would like to solve thiese equations without have to
manipulate them by hand. anybody with any ideas would be welcomed,
Please email me as my newserver is spotty at best.
Thanks
Troy
s2700114@nickel.laurentian.ca
eone og[10, c] Ð(-38530+ 36*t)/(1.987*2.303*t); etwo Log[10, b] +
0.5*Log[10, o] - Log[10, c] Ð(-23000+2167*t)/(1.987*2.303*t);
ethree + c + o Ð1;
efour /o Ð0.5;
Prev by Date:
**nasty integrals that Mathematica can't do**
Next by Date:
**Calc formula from table**
Prev by thread:
**Re: nasty integrals that Mathematica can't do**
Next by thread:
**Calc formula from table**
| |