Can someone pls help on this problem in Mathematica

  • #1

Main Question or Discussion Point

Hi all,

I got stucked with the problem with regard to Do-Loop and solving simultaneous equations together.

Please help me on this matter and the file is attached, Iam using Mathematica 7

Thanks
 

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Answers and Replies

  • #2
1,069
29
In Task 1 in (W1r)=(3m*n(Ar+Ar+1)...)) there is a missing ; and there are missing or extra {} or levels in your matrix equation that give errors. Once I try to guess what to do to fix those then it grinds away producing 37500 matrix equations and I assume it will finish in the future.

Task 2 is written in a very strange way but it does what you seem to request.

Task 3 is very difficult to understand. Substitute A0,A1,B0,B1 from Task 2 is clear. But substitute in what? In Task1? Sum W1r=0 what? In Task1?

To do substitutions in an expression usually you use
expression//.{A0-> -U10,A1-> -U11,B0-> -V10,B1-> -V11}
and that will replace all A0, A1,B0,B1 with your desired values in expression.

To Sum usually you use
Sum[W1r=0,{m,1,99,2},{n,1,99,2}]
if you have assigned the desired expression to W1r.

But it is not clear that I am answering what you have asked for or you have asked for what you need.

Perhaps the physics forums OtherSciences->Math&ScienceSoftware would be a better place to ask Mathematica syntax questions.
 
  • #3
1,069
29
Perhaps you can see how to adapt this very simple example to your actual problem.

In[4]:= w=3m*n*a+8n^2*b;
rules=Solve[{a+u==0,b+v==0},{a,b}];
Sum[w//.rules,{m,1,5,2},{n,0,3,1}]

Out[6]= {-162 u-336 v}
 

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