qfunc

Syntax

y = qfunc(x)

Description

example

y = qfunc(x) returns the output of the Q function for each element of the real array x. The Q function is one minus the cumulative distribution function of the standardized normal random variable.

Input Arguments

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Input, specified as a real scalar or array.

Output Arguments

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Q function output, returned as a real scalar or array having the same dimensions as input x.

Examples

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Determine the values of the Q function for an input vector.

x = -4:0.1:4;
y = qfunc(x);

Plot the results.

plot(x,y)
grid

Convert an input Eb/No in dB to its linear equivalent.

ebnodB = 7;
ebno = 10^(ebnodB/10);

Determine the QPSK error probability, Pb, given that:

Pb=Q(2EbNo).

Pb = qfunc(sqrt(2*ebno))
Pb = 7.7267e-04

Algorithms

For a scalar x, the formula is

Q(x)=12πxexp(t2/2)dt

The Q function is related to the complementary error function, erfc, according to

Q(x)=12erfc(x2)

See Also

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Introduced before R2006a