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Re: What is causing this error message?

  • To: mathgroup at
  • Subject: [mg57575] Re: [mg57537] What is causing this error message?
  • From: Murray Eisenberg <murray at>
  • Date: Wed, 1 Jun 2005 06:02:47 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <>
  • Reply-to: murray at
  • Sender: owner-wri-mathgroup at

You have (at least) two errors in the input cell you show:

(1) Presumably you want the terms x y and x y^2 rather than xy and xy^2. 
  (The latter pair would refer to a two-letter variable "xy".)

(2) You need the double-equal sign == to indicate an equation.  (By 
contrast, the single-equals = is used to assign values, which is 
shorhand for the Set function.)

Such examples are a good way to learn how Mathematica works, but it's 
also a very good idea to do start at the beginning of the part "A 
Practical Introduction to Mathematica" to learn such basic syntactical 
notions as well as the semantics of them.

Bookreader wrote:
> 	NSolve[{x^3y + xy - 10 = 0, xy^2 - xy + 6 = 0}, {x, y}]
> 	Set::write: Tag Plus in -10 + x y + x^3  y is Protected. More?
> 	Please tell me how to correct this.

Murray Eisenberg                     murray at
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

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