[Date Index]
[Thread Index]
[Author Index]
Exponent function
*To*: mathgroup at smc.vnet.net
*Subject*: [mg7807] Exponent function
*From*: Raya Firsov-Khanin <raya at mech.ed.ac.uk>
*Date*: Sat, 12 Jul 1997 02:45:49 -0400
*Sender*: owner-wri-mathgroup at wolfram.com
Hello,
I've noticed the following strange feature of
Exponent[expr, arg, List]
function of Mathematica. Suppose I want to
find all powers of x in the expression of the type
test = x + x^(1+a) + x^(-1+a) + x^2
then Exponent[test, x, List] gives the correct result
{1, 2, 1-a, -1+a}.
Suppose now, I add x^(-1) to test:
test1 = test + x^(-1)
then
Exponent[test1, x, List] gives a result {-1, -1, 1, 1, 2}.
For expressions like
test2 = test + x^(-n) the result of Exponent[] is correct
{1, 2, 1-a, -1+a, -n}, while for expressions where n is specified,
e.g. n=1, 2, 3, ... the result is always wrong.
I need to use Exponent function in a program that
should solve nonlinear problems using Multiple Scale Method. I need to
identify exponential frequencies of different terms in the equations, and
to study under what conditions they become resonant.
Any suggestions on how I can make Exponent function to give correct
results? Or may be there are some other ways to find powers of x in the
expressions of the type written above.
Any help would be appreciated. I already spent a morning trying to solve
this puzzle.
Thanks a lot.
Raya
Prev by Date:
**Re: graphics import/conversion bug?**
Next by Date:
**Re: character problem**
Previous by thread:
**Question regarding expressions with Sum[...]**
Next by thread:
**Re: character problem**
| |