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I am intending to use NestWhile in finding a solution with random real values as parameter.

NestWhile[{b2, b3, k1, d2, d3, k2, g2, k3} = RandomReal[2, 8], 
 RR1 = Solve[{F11 == 0 && F12 == 0 && F13 == 0 && F21 == 0 && 
     F22 == 0 && F23 == 0 && F31 == 0 && F32 == 0 && F33 == 0}, {a0, 
    a1, b1, c0, c1, d1, f0, f1, g1}], 
 Element[{a0 /. RR1[[1]]}, Reals] == False &, 1, 5]

However, when I test my code (at most 5 iterations), I found that each iteration has the same random real values.

I was wondering that how can I modify the code such that I can get the different random real values for different iteration within the NestWhile loop.

Thanks for your help in advance!

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  • $\begingroup$ The code you posted does not evaluate without giving a message. $\endgroup$
    – Jason B.
    Commented Sep 10, 2020 at 15:43
  • $\begingroup$ Maybe you should use a While loop. Doing assignments to global state inside functional constructs is dodgy. Try this pastebin.com/UGSCdUzY - it should be close to what you need. $\endgroup$
    – flinty
    Commented Sep 10, 2020 at 16:16
  • $\begingroup$ @mikado What's wrong with pastebin? We often advise people to post code that's too long to that site. $\endgroup$
    – Michael E2
    Commented Sep 10, 2020 at 17:07

1 Answer 1

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Here is a simple example, showing how you can get a different random number on each iteration of a NestWhile. Note that the assignment to a uses delayed evaluation (:= rather than =)

a := RandomReal[]

NestWhile[Append[#, a] &, {}, Length[#] < 10 &]
(* {0.358648, 0.262051, 0.597893, 0.654873, 0.20104, 0.389616, \
0.764424, 0.0774252, 0.63444, 0.58011} *)
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