Geometric probability density function
y = geopdf(x,p)
y = geopdf(x,p) returns
the probability density function (pdf) of the geometric distribution
at each value in
x using the corresponding probabilities
be vectors, matrices, or multidimensional arrays that all have the
same size. A scalar input is expanded to a constant array with the
same dimensions as the other input. The parameters in
lie on the interval
Suppose you toss a fair coin repeatedly, and a "success" occurs when the coin lands with heads facing up. What is the probability of observing exactly three tails ("failures") before tossing a heads?
To solve, determine the value of the probability density function (pdf) for the geometric distribution at
x equal to
3. The probability of success (tossing a heads)
p in any given trial is
x = 3; p = 0.5; y = geopdf(x,p)
y = 0.0625
The returned value of
y indicates that the probability of observing exactly three tails before tossing a heads is
The probability distribution function (pdf) of the geometric distribution is
where p is the probability of success, and x is the number of failures before the first success. The result y is the probability of observing exactly x trials before a success, when the probability of success in any given trial is p. For discrete distributions, the probability distribution function is also known as the probability mass function (pmf).
This function fully supports GPU arrays. For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).