Solving equation in Mathematica

  • Context: Mathematica 
  • Thread starter Thread starter EngWiPy
  • Start date Start date
  • Tags Tags
    Mathematica
Click For Summary

Discussion Overview

The discussion revolves around solving a mathematical equation in Mathematica, specifically finding parameters Na and Q that satisfy a given expression equal to 10^{-10}. The scope includes technical explanations of Mathematica functions and potential approaches to finding solutions.

Discussion Character

  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • The original poster presents a code snippet using the Solve function to find parameters Na and Q but indicates that it does not work as intended.
  • Some participants suggest that not all equations have analytical solutions and recommend using numerical methods like FindRoot instead of Solve.
  • A later reply clarifies that the syntax for FindRoot differs from that of Solve, suggesting the original poster consult the help menu for guidance.

Areas of Agreement / Disagreement

Participants generally agree that analytical solutions may not be available for all equations and that numerical methods could be necessary. However, there is no consensus on the specific implementation details or the effectiveness of the proposed solutions.

Contextual Notes

Participants note the limitations of the Solve function and the need for understanding the syntax differences between Solve and FindRoot, but do not resolve the specific challenges faced in the original equation.

EngWiPy
Messages
1,361
Reaction score
61
Hello,

I have the following code to find the parameters Na and Q that make the expression equals 10^{-10}:

Code:
Na =.;
Q =.;
MGF[s_, gC_] := 1/(1 - gC*s);
SNRdB = 0;
SNR = 10^(SNRdB/10);
gC = 0.5*SNR;
p = gA*gB;
A = 23;
Solve[((E^(A/2)*2^-Q)/SNR \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(q = 0\), \(Q\)]\(-
\*SuperscriptBox[\(1\), \(Na + q + 1\)]\)*Binomial[Q, q]*Re[
\*FractionBox[\(MGF[\(-
\*FractionBox[\(A + \((2*Pi*I \((Na + q + 1)\))\)\), \(2\ SNR\)]\), 
          gC]\), 
FractionBox[\(A + 2*Pi*I \((Na + q + 1)\)\), \(2\ SNR\)]]]\)) == 
   10^-10, {Na, Q}]

But it doesn't work? Anyone have any idea about how solving this equation?

Thanks in advance
 
Physics news on Phys.org
There are not analytical solutions for all equations. Functions like Solve, Reduce, DSolve, etc. will not always be able to find a solution. In such cases you can only find numerical solutions using e.g. FindRoot.
 
DaleSpam said:
There are not analytical solutions for all equations. Functions like Solve, Reduce, DSolve, etc. will not always be able to find a solution. In such cases you can only find numerical solutions using e.g. FindRoot.

Thanks DaleSpam for replying,

So, you are saying that If I replace the "Solve" command by "FindRoot", I may get a result?

Regards
 
The syntax for FindRoot is a little different than for Solve. You should use the help menu to find the new syntax and some examples.
 
DaleSpam said:
The syntax for FindRoot is a little different than for Solve. You should use the help menu to find the new syntax and some examples.

Ok, I will. Thanks again
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 11 ·
Replies
11
Views
5K
  • · Replies 2 ·
Replies
2
Views
3K
Replies
10
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 19 ·
Replies
19
Views
3K