randsrc

Generate random matrix using prescribed alphabet

Syntax

out = randsrc

out = randsrc(m)

out = randsrc(m,n)

out = randsrc(m,n,alphabet)

out = randsrc(m,n,[alphabet; prob])

out = randsrc(m,n,___,seed)

out = randsrc(m,n,___,streamhandle)

Description

out = randsrc generates a random scalar that is either -1 or 1, with equal probability.

out = randsrc(m) generates an m-by-m random bipolar matrix. Each entry independently takes the value -1 or 1 with equal probability.

out = randsrc(m,n) generates an m-by-n random bipolar matrix. Each entry independently takes the value -1 or 1 with equal probability.

out = randsrc(m,n,alphabet) generates an m-by-n matrix, with each entry independently chosen from the entries in the row vector alphabet. Each entry in alphabet occurs in out with equal probability. Duplicate values in alphabet are ignored.

out = randsrc(m,n,[alphabet; prob]) generates an m-by-n matrix, with each entry independently chosen from the entries in the row vector alphabet. Duplicate values in alphabet are ignored. The row vector prob lists corresponding probabilities, so that the symbol alphabet(k) occurs with probability prob(k), where k is any integer between one and the number of columns of alphabet. The elements of prob must add up to 1.

out = randsrc(m,n,___,seed) accepts input combinations from prior syntaxes and a seed value, for initializing the uniform random number generator, rand.

out = randsrc(m,n,___,streamhandle) accepts input combinations from prior syntaxes and a random stream handle to generate uniform random noise samples by using rand. Providing a random stream handle or using the reset (RandStream) function on the default random stream object enables you to generate repeatable noise samples. If you want to generate repeatable noise samples, then either reset the random stream input before calling randsrc or use the same seed input. For more information, see RandStream.

Examples

Generate Random Matrix from Prescribed Alphabet

Generate a 10-by-10 matrix from the set of {-3,-1,1,3}.

out = randsrc(10,10,[-3 -1 1 3])

out = 10×10

     3    -3     1     1    -1    -1     3     3    -1    -3
     3     3    -3    -3    -1     1    -1    -1     3    -3
    -3     3     3    -1     3     1     1     3     1     1
     3    -1     3    -3     3    -3     1    -3     1     3
     1     3     1    -3    -3    -3     3     3     3     3
    -3    -3     3     3    -1    -1     3    -1    -1    -3
    -1    -1     1     1    -1     3     1    -3     3     1
     1     3    -1    -1     1    -1    -3    -1     3    -1
     3     3     1     3     1     1    -3     1    -1    -3
     3     3    -3    -3     3    -3    -1    -1     1    -1

Plot the histogram. Each of the four possible element values occur with equal probability. Your values might differ.

histogram(out,[-4 -2 0 2 4])

Generate a matrix in which the likelihood of a -1 or 1 is four times higher than the likelihood of a -3 or 3.

out = randsrc(10,10,[-3 -1 1 3; 0.1 0.4 0.4 0.1])

out = 10×10

    -1    -1    -1    -1     1    -1     1    -1     1     3
     1    -3     3     3     1    -3    -1    -1    -1     1
    -1    -1    -3    -1    -1     3    -1     1     1    -1
     1     3     1    -1     1     3    -1    -3    -1    -1
    -1    -1     1    -1    -1    -1    -3    -3     1    -1
     1     1     1    -1    -3    -1    -1    -1    -1    -1
    -1     1    -3     1    -1    -1     3     1    -1     1
     1     3    -1     1    -1     3     3     1     1     1
     1    -3    -1     1    -1    -1     1     1     1     1
     1    -1     1    -1    -1    -1    -3    -1    -3     1

Plot the histogram. Values of -1 and 1 are more likely.

histogram(out,[-4 -2 0 2 4])

Input Arguments

m — Bipolar matrix size

1 (default) | scalar

Size of random bipolar matrix, specified as a scalar. If n is specified, then m is the row size of the random bipolar matrix.

Data Types: double

n — Bipolar matrix column size

1 (default) | scalar

Column size of random binary matrix, specified as a scalar.

Data Types: double

alphabet — Possible element values

[-1 1] (default) | vector | matrix

Possible elements of output vector or matrix. If alphabet is a row vector, the contents of alphabet define which possible elements randsrc output. If alphabet is a two-row matrix, then the first row is defines the possible elements, and the second row defines the probabilities for each corresponding element in the first row. The elements of the second row must sum to one. If all entries of alphabet are distinct, then the probability distribution is uniform.

Data Types: double
Complex Number Support: Yes

prob — Element probabilities

[0.5 0.5] (default) | vector

Row vector of probabilities that correspond to elements of the corresponding alphabet vector.

Data Types: double

seed — Seed value

scalar

Seed value for initializing the uniform random number generator, rand.

Data Types: double

streamhandle — Random stream handle

RandStream Object

Random stream handle to generate uniform random noise samples by using rand. Providing a random stream handle or using the reset (RandStream) function on the default random stream object enables you to generate repeatable noise samples. If you want to generate repeatable noise samples, then either reset the random stream input before calling randsrc or use the same seed input. For more information, see RandStream.

Data Types: double

Output Arguments

out — Random matrix output

scalar | vector | matrix

Random output, returned as a scalar, vector, or matrix. The dimensions of the output are specified by arguments m and n, otherwise it is a 1-by-1 scalar. The possible elements of the output and their probabilities are specified by alphabet, prob respectively, otherwise the elements of the output are -1 and 1, with equal distribution.

Data Types: double

Version History

Introduced before R2006a