Let $U sim textrm{Unif}(0, pi/ 2)$. Find the PDF of $sin(U)$.












1












$begingroup$


This is almost the same as Suppose that X ∼ U ( $− π/2$ , $π/2$ ) . Find the pdf of Y = tan(X)., but making sure I am understanding the process:




Let $U sim textrm{Unif}(0, pi/ 2)$. Find the PDF of $sin(U)$.




$$begin{align}
F_Y(y) &= P(Y<y) = P(sin(u)<y) = P(u < sin^{-1}(y)) \
&=F_U(sin^{-1}(y)) = int_0^{sin^{-1}(y)}frac{1}{frac{pi}{2}}du \
&= frac{1}{frac{pi}{2}}u |_0^{sin^{-1}(y)} \
&= frac{2}{pi}sin^{-1}(y) \
end{align} $$



That is the CDF. To find the PDF, take the derivative with respect to $y$ to get:



$$ frac{2}{pi}frac{1}{sqrt{1-y^2}} $$




  1. Is the work & logic correct?

  2. Is the support of $Y$ the same as the support for U: $[0,pi/2]$?










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$endgroup$








  • 2




    $begingroup$
    The support for $Y$ is $[0,1]$. Always good to confirm that the PDF integrates to 1 over $[0,1]$. In this case it does. You can compute the integral by substituting $y = sin theta$.
    $endgroup$
    – Aditya Dua
    Dec 8 '18 at 22:21
















1












$begingroup$


This is almost the same as Suppose that X ∼ U ( $− π/2$ , $π/2$ ) . Find the pdf of Y = tan(X)., but making sure I am understanding the process:




Let $U sim textrm{Unif}(0, pi/ 2)$. Find the PDF of $sin(U)$.




$$begin{align}
F_Y(y) &= P(Y<y) = P(sin(u)<y) = P(u < sin^{-1}(y)) \
&=F_U(sin^{-1}(y)) = int_0^{sin^{-1}(y)}frac{1}{frac{pi}{2}}du \
&= frac{1}{frac{pi}{2}}u |_0^{sin^{-1}(y)} \
&= frac{2}{pi}sin^{-1}(y) \
end{align} $$



That is the CDF. To find the PDF, take the derivative with respect to $y$ to get:



$$ frac{2}{pi}frac{1}{sqrt{1-y^2}} $$




  1. Is the work & logic correct?

  2. Is the support of $Y$ the same as the support for U: $[0,pi/2]$?










share|cite|improve this question











$endgroup$








  • 2




    $begingroup$
    The support for $Y$ is $[0,1]$. Always good to confirm that the PDF integrates to 1 over $[0,1]$. In this case it does. You can compute the integral by substituting $y = sin theta$.
    $endgroup$
    – Aditya Dua
    Dec 8 '18 at 22:21














1












1








1





$begingroup$


This is almost the same as Suppose that X ∼ U ( $− π/2$ , $π/2$ ) . Find the pdf of Y = tan(X)., but making sure I am understanding the process:




Let $U sim textrm{Unif}(0, pi/ 2)$. Find the PDF of $sin(U)$.




$$begin{align}
F_Y(y) &= P(Y<y) = P(sin(u)<y) = P(u < sin^{-1}(y)) \
&=F_U(sin^{-1}(y)) = int_0^{sin^{-1}(y)}frac{1}{frac{pi}{2}}du \
&= frac{1}{frac{pi}{2}}u |_0^{sin^{-1}(y)} \
&= frac{2}{pi}sin^{-1}(y) \
end{align} $$



That is the CDF. To find the PDF, take the derivative with respect to $y$ to get:



$$ frac{2}{pi}frac{1}{sqrt{1-y^2}} $$




  1. Is the work & logic correct?

  2. Is the support of $Y$ the same as the support for U: $[0,pi/2]$?










share|cite|improve this question











$endgroup$




This is almost the same as Suppose that X ∼ U ( $− π/2$ , $π/2$ ) . Find the pdf of Y = tan(X)., but making sure I am understanding the process:




Let $U sim textrm{Unif}(0, pi/ 2)$. Find the PDF of $sin(U)$.




$$begin{align}
F_Y(y) &= P(Y<y) = P(sin(u)<y) = P(u < sin^{-1}(y)) \
&=F_U(sin^{-1}(y)) = int_0^{sin^{-1}(y)}frac{1}{frac{pi}{2}}du \
&= frac{1}{frac{pi}{2}}u |_0^{sin^{-1}(y)} \
&= frac{2}{pi}sin^{-1}(y) \
end{align} $$



That is the CDF. To find the PDF, take the derivative with respect to $y$ to get:



$$ frac{2}{pi}frac{1}{sqrt{1-y^2}} $$




  1. Is the work & logic correct?

  2. Is the support of $Y$ the same as the support for U: $[0,pi/2]$?







random-variables uniform-distribution






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edited Dec 8 '18 at 22:11









Andrews

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asked Dec 8 '18 at 21:56









user603569user603569

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  • 2




    $begingroup$
    The support for $Y$ is $[0,1]$. Always good to confirm that the PDF integrates to 1 over $[0,1]$. In this case it does. You can compute the integral by substituting $y = sin theta$.
    $endgroup$
    – Aditya Dua
    Dec 8 '18 at 22:21














  • 2




    $begingroup$
    The support for $Y$ is $[0,1]$. Always good to confirm that the PDF integrates to 1 over $[0,1]$. In this case it does. You can compute the integral by substituting $y = sin theta$.
    $endgroup$
    – Aditya Dua
    Dec 8 '18 at 22:21








2




2




$begingroup$
The support for $Y$ is $[0,1]$. Always good to confirm that the PDF integrates to 1 over $[0,1]$. In this case it does. You can compute the integral by substituting $y = sin theta$.
$endgroup$
– Aditya Dua
Dec 8 '18 at 22:21




$begingroup$
The support for $Y$ is $[0,1]$. Always good to confirm that the PDF integrates to 1 over $[0,1]$. In this case it does. You can compute the integral by substituting $y = sin theta$.
$endgroup$
– Aditya Dua
Dec 8 '18 at 22:21










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$begingroup$

Per Aditya Dua: The support for Y is [0,1]. Always good to confirm that the PDF integrates to 1 over [0,1]. In this case it does. You can compute the integral by substituting y=sinθ.






share|cite|improve this answer









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    $begingroup$

    Per Aditya Dua: The support for Y is [0,1]. Always good to confirm that the PDF integrates to 1 over [0,1]. In this case it does. You can compute the integral by substituting y=sinθ.






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      Per Aditya Dua: The support for Y is [0,1]. Always good to confirm that the PDF integrates to 1 over [0,1]. In this case it does. You can compute the integral by substituting y=sinθ.






      share|cite|improve this answer









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        0





        $begingroup$

        Per Aditya Dua: The support for Y is [0,1]. Always good to confirm that the PDF integrates to 1 over [0,1]. In this case it does. You can compute the integral by substituting y=sinθ.






        share|cite|improve this answer









        $endgroup$



        Per Aditya Dua: The support for Y is [0,1]. Always good to confirm that the PDF integrates to 1 over [0,1]. In this case it does. You can compute the integral by substituting y=sinθ.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 8 '18 at 23:25









        user603569user603569

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