Re: Distribution of x^3?




Ray Koopman wrote:

Because the PDF is defined as the derivative of the CDF,
and the CDF of a uniform variable is easy to work with.

X ~ Uniform[0,1].

CDF: F_X[x] = P[X <= x]
= x, 0 <= x <= 1.

Y = X^3.

CDF: F_Y[y] = P[Y <= y]
= P[X^3 <= y]
= P[X <= y^(1/3)]
= y^(1/3), 0 <= y <= 1.

PDF: f_Y[y] = dF_Y[y]/dy
= (1/3) y^(-2/3).

Wow, it was really simple. I had already read the articles you
suggested, but I was doing all sorts of crazy calculations :-(. Many
thanks, Mr. Koopman!!

.



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