| Author |
Comment/Response |
Aaron Honecker
|
 09/13/00 1:51pm
>I need help for relatively an easy problem;
>
>I am solving the following system of equations:
>
>Solve[{Lamda1 - Lamda2 == 0, Lamda2 - Lamda3 == 0, Lamda3 - Lamda4 == 0,
> Lamda4 - Lamda5 == 0}, {x11, x12, x13, x14}]
>
>and it gives me more than 100 solutions. However, I want to have only
>positive ones. In this case, there is only one solution that all variables
>are positive. In order to find out this solution, I am doing an inspection
>by eyes. I wanna ask whether there is anyway that I can do the inspection
>in the search of positive solutions only using Mathematica commands? That is, I just wanna pick positive solution(s) if any...
>
>Thanks...
One way that you can extract the positive solutions is with the following:
S=Solve[{Lamda1 - Lamda2 == 0, Lamda2 - Lamda3 == 0, Lamda3 - Lamda4 == 0,
Lamda4 - Lamda5 == 0}, {x11, x12, x13, x14}]
Cases[S, {x11 -> _?Positive, x12 -> _?Positive, x13 -> _?Positive,
x14 -> _?Positive}]
This will extract all solutions (if any) where x11, x12, x13, x14 are all positive
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