[Date Index]
[Thread Index]
[Author Index]
Re: Looking for help with "Reduce" command for use with
*To*: mathgroup at smc.vnet.net
*Subject*: [mg98038] Re: [mg98002] Looking for help with "Reduce" command for use with
*From*: Bob Hanlon <hanlonr at cox.net>
*Date*: Sat, 28 Mar 2009 05:45:09 -0500 (EST)
*Reply-to*: hanlonr at cox.net
pts = {x, y} /. {Reduce[
{x^3 + y^3 == 6 x*y, -4 <= x <= 3,
Element[x, Integers], Element[y, Reals]},
{x, y}] // ToRules} /. Root[a__] :> N[Root[a]]
{{-4, 2.214295128870666}, {-3, 1.3601929545492113},
{-2, 0.6443707092521711}, {-1, 0.1659055841222127}, {0, 0},
{1, -2.528917957294362}, {1, 0.16744919110853515},
{1, 2.3614687661858267}, {2, -3.7587704831436337},
{2, 0.6945927106677213}, {2, 3.064177772475912},
{3, (1/2)*(-3 - 3*Sqrt[5])}, {3, (1/2)*(-3 + 3*Sqrt[5])}, {3, 3}}
Bob Hanlon
---- Gary Church <gary.church1 at comcast.net> wrote:
=============
Hello,
My first post to this newsgroup :-)
I'm a mathematics instructor at a two-year college. Currently, I'm
trying to explain implicit differentiation and implicitly defined
functions to my students.
To illustrate, I'm using the famous folium of Descartes:
x^3 + y^3 = 6xy
I want to generate all the pairs of real (x,y) solutions for x taking
integer values from -4 to 3, and to then plot these pairs as points on
the curve defined by the equation.
So far I've come up with:
pts = Table[{i, Reduce[curve /. {x -> i}, y, Reals] // N}, {i, -4, 3}]
which gives me a table with rows like:
-4 y=2.2143
or like:
2 y=-3.75877 \[Or] y=0.694593 \[Or] y=3.06418
where the "\[Or]" is the logical "or" symbol.
Of course this is not what I want. I want a list of pairs like:
(-4,2.2143), (2,-3.75877), (2,0.694693), (2,3.06418), etc...
so I can plot them as points.
Can any of you Mathematica mavens provide this neophyte with an elegant
solution?
Thanks much,
Gary
Prev by Date:
**Re: How do I hide all input in a Mathematica notebook?**
Next by Date:
**Re: pdf export problem**
Previous by thread:
**Re: Looking for help with "Reduce" command for use with my Calculus**
Next by thread:
**Using a variable set elsewhere within a function that has attribute**
| |