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Poisson cumulative distribution function (cdf).
Syntax
P = poisscdf(X,LAMBDA)
Description
poisscdf(X,LAMBDA) computes the Poisson cdf with parameter settings LAMBDA at the values in X. The arguments X and LAMBDA must be the same size except that a scalar argument functions as a constant matrix of the same size of the other argument. The parameter, LAMBDA, is positive. The Poisson cdf is:
Examples
For example, consider a Quality Assurance department that performs random tests of individual hard disks. Their policy is to shut down the manufacturing process if an inspector finds more than four bad sectors on a disk. What is the probability of shutting down the process if the mean number of bad sectors (
) is two?
probability = 1 - poisscdf(4,2)
probability =
0.0527
About 5% of the time, a normally functioning manufacturing process will produce more than four flaws on a hard disk.
Suppose the average number of flaws () increases to four. What is the probability of finding fewer than five flaws on a hard drive?
probability = poisscdf(4,4)
probability =
0.6288
This means that this faulty manufacturing process continues to operate after this first inspection almost 63% of the time.