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Mathematics Geometry Wolfram Language

Generate random points in a unit circle using a "For" loop?

Chiel Geeraert

Posted 7 years ago

I am new to Mathematica and I have a problem with the "For" statement. I am often in doubt where to place a "," or a ";". I am stuck with the following : I want to generate random points in a unit circle with the following function : randompunten[n_] := Module[{p = n, r, angle, lis, i}, lis = {}; For[i = 0; r = RandomReal[], angle = RandomReal[2 \[Pi]], i <= p; i++; lis = Append[lis, Point[{r Cos[angle], r Sin[angle]]}]]]; lis] The result is an empty lis NB : I just found out that this is not the right way but aside of that : what am I doing wrong in the code ? (When I do the Append statement outside the module things work fine .

POSTED BY: Chiel Geeraert

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Chiel Geeraert

Posted 7 years ago

Even more simple ! Alas, function not available in my version. Thank you for your reply, Chiel Geeraert.

POSTED BY: Chiel Geeraert

Henrik Schachner

Henrik Schachner, Radiation Therapy Center, Weilheim, Germany

Posted 7 years ago

Just for completeness: The function `RandomPoint` should at least be mentioned.

POSTED BY: Henrik Schachner

Alexander Trounev

Alexander Trounev, A&E Trounev IT Consulting

Posted 7 years ago

randompunten[n_] := Module[{p = n, r, angle, lis, i}, lis = {}; For[i = 0, i < p, i++, {r = RandomReal[], angle = RandomReal[2 \[Pi]], lis = Append[lis, Point[{r Cos[angle], r Sin[angle]}]]}]; lis] {Graphics[{Red, randompunten[5], Blue, Circle[{0, 0}, 1]}], Graphics[{Red, randompunten[100], Blue, Circle[{0, 0}, 1]}]}

randompunten[n_] := Module[{p = n, r, angle, lis, i}, lis = {};
  For[i = 0, i < p, 
   i++, {r = RandomReal[], angle = RandomReal[2 \[Pi]],
    lis = Append[lis, Point[{r Cos[angle], r Sin[angle]}]]}]; lis]
{Graphics[{Red, randompunten[5], Blue, Circle[{0, 0}, 1]}], 
 Graphics[{Red, randompunten[100], Blue, Circle[{0, 0}, 1]}]}

fig 1