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I am trying to solve 8 coupled algebraic equations. I have simplified coefficients of unknowns by using Assumptions -> tp > 0 && tp < 2 Pi. Answers to the equations are very complicated. I can not simplify them because it takes a lot of time (After waiting for 17 hours, the code for simplifying solutions has not finished.)

In the solutions, there are lots of terms which can be written in a more simplified manner, but Mathematica's output (solutions) are not automatically simplified. There are lots of terms such as:

(-(((3 a - 2 H) Cos[tp]^2)/(6 a eta π)) - ((3 a - 2 H) Sin[tp]^2)/(6 a eta π))

What should I do? Can I use assumption tp > 0 && tp < 2 Pi to avoid this problem?

m_goldberg
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Holger Mate
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1 Answers1

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Yes, there is a global variable for this purpose:

$Assumptions = tp > 0 && tp < 2 Pi
Andrew
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  • $Assumptions is used only by functions that accept the option Assumptions. For functions like Solve, NSolve, or Reduce the assumptions should also be included as constraints, e.g., Solve[eqns && $Assumptions, vars]//Simplify – Bob Hanlon Jun 26 '18 at 14:43
  • Thank you for your answer. How should I use it when solving the equation? – Holger Mate Jun 27 '18 at 05:52
  • It is described in the comment of @Bob Hanlon. – Andrew Jun 27 '18 at 06:36
  • Shouldn't I use solution1 = solution1 /. sol[[1, 1]]; befor simplification? @BobHanlon – Holger Mate Jun 27 '18 at 07:39
  • Since neither solution1 nor sol are defined in your question or the answer, your comment makes no sense to me. If you are asking whether you should defer the use of Simplify that is up to you. – Bob Hanlon Jun 27 '18 at 13:49