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In the following plot, one of the two functions

{-par, par}

defined by 

par = (2 + 3 Subscript[y, 3] - 
 9 (Subscript[y, 3])^2 + ((1 + 3 Subscript[y, 3])^2 (4 - 
     36 (Subscript[y, 1])^2 - 12 Subscript[y, 3] + 
     9 (Subscript[y, 3])^2))^(1/2))^(1/2)/(3 Sqrt[2]);

has an erroneously reduced domain:

Plot3D[{-par, par}, {Subscript[y, 3], -(1/3), 2/3}, 
{Subscript[y, 1], -(Subscript[y, 3] - 2/3)/2, 
(Subscript[y, 3] - 2/3)/2}, BoxRatios -> Automatic]

When I replace the variables 

{ Subscript[y, 1], Subscript[y, 3] }

by 

{ a, b }

then the error disappears.

I am using Mathmatica 9 on Mac OS X

Stephan
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    The community wiki here on basic syntax issues http://mathematica.stackexchange.com/a/18395/1952 links to the canonical (for me) answers to how and why not to use subscripts as variables - http://mathematica.stackexchange.com/a/1005/1952 and http://mathematica.stackexchange.com/a/871/1952 – Charlotte Hadley Apr 22 '15 at 11:52
  • Thanks. Instructions http://mathematica.stackexchange.com/a/18395/1952 suggest to use indexed variables like a[1] or a[2]. However I get the same domain error in the above plot when I replace Subscript[y, 1] by a[1] and Subscript[y, 3] by a[2]. Help? How to use indexed variables in a general situation? – Stephan Apr 23 '15 at 07:05
  • unfortunately I can't explain why that is still playing up. Hopefully another user will be able to help. – Charlotte Hadley Apr 23 '15 at 11:22

0 Answers0