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# getProbability

System object: comm.CCDF
Package: comm

Get the probability for a given relative power value

## Syntax

P = getProbability(H,R)

## Description

P = getProbability(H,R) finds the probability, P, of the power level of the signal of interest being R dBs (if PowerUnits equals 'dBW', or 'dBm') or Watts (if PowerUnits equals 'Watts') above its average power. P is a column vector with the i-th element corresponding to the probability value for the i-th input channel. Input R can be a double precision scalar or a vector with a number of elements equal to the number of input channels. If R is a scalar, then all the probability values in P correspond to the same relative power specified in R. If R is a vector, then the ith element of P contains a probability value for the i-th channel and for the relative power specified in the i-th element of R.

For the i-th input channel, this method evaluates the CCDF curve at relative power value R(i)

## Examples

Obtain CCDF curves for a unit variance AWGN signal and a dual- tone signal. Find the probability that the AWGN signal power is 5 dB above its average power and that the dual-tone signal power is 3 dB above its average power.

``` n = [0:5e3-1].';
s1 = randn(5e3,1);                    % AWGN signal
s2 = sin(0.01*pi*n)+sin(0.03*pi*n);   % dual-tone signal
hCCDF = comm.CCDF;
step(hCCDF,[s1 s2]);
plot(hCCDF)                           % plot CCDF curves
legend('AWGN','Dual-tone')
P = getProbability(hCCDF,[5 3])       % get probabilities```