Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2008

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Re: symbolic evaluation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg87050] Re: [mg87026] Re: symbolic evaluation
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Sun, 30 Mar 2008 01:16:38 -0500 (EST)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200803290924.EAA16507@smc.vnet.net>
  • Reply-to: murray at math.umass.edu

You're still stubbornly confusing two basically different things in 
Mathematica...

a = b is NOT an equation in Mathematica!  It is an abbreviation for 
Set[a,b], which immediately gives a the value of b.

   7x = 14 (* syntactically forbidden; error message results *)

a == b  (with TWO equal signs) is an equation in Mathematica, which may 
have the value True or False (in case Mathematica has sufficient 
information already about a and b to decide this) or just return the 
equation if it cannot yet decide the truth or falsity.

   7x == 14   (* input *)
7x == 14     (* output result *)

You really want to transform the equation 7x==14 into the equation x==2? 
  Easy:

   Reduce[7x == 14, x]      (* input *)
x == 2                     (* output *)


Under ordinary circumstances, you would not want to "transform" your 
equation into the form you say.

p3aul wrote:
> Thank you all for your answers, but they all result in Mathematica "solving" the equation and giving the answer 2, which is not what I need. What I need is for Mathematica to transpose the formula giving as out put x = 14/7. I beginning to believe that mathematica can't do it because the designer didn't put that capability in it. This must be a hard concept for a computer to do. It just seems simple to me. What's wrong with "out[1]= {{x -> 14/2}}" Which output I can't seem to get.
> Paul:(
> 

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


  • Prev by Date: Re: IsIntegerOrFloat
  • Next by Date: Re: IsIntegerOrFloat
  • Previous by thread: Re: symbolic evaluation
  • Next by thread: Re: symbolic evaluation