Fix the random values

Hi everyone, I have this below code of matlab, which generates random values.

data_size = 8; % not necessarily a power-of-2
data_range = [0 255];
data = randi(data_range, data_size, 1) + 1i*randi(data_range, data_size, 1); % Complex Data

I am new at matlab. Is there a way to fix these random values. I need it because i am stuck with some debugging.

Answer 1

[Star Strider]

The rng function controls the seed.

Example —

rng(1)
r1 = randi(9,1,10)

r1 = 1×10

4 7 1 3 2 1 2 4 4 5

rng(1)
r2 = randi(9,1,10)

r2 = 1×10

4 7 1 3 2 1 2 4 4 5

There are a number of helpful links in the See Also section of the documentation that explain it.

.

[Manu Chaudhary]

Yes, in my code we are using randi but getting different results everytime.

[Walter Roberson]

rng() controls the sequence of values.

[Star Strider]

You will need to set the rng seed every time before calling any of the random number generators.

My code example illustrates that.

However once reset, the random numbers should produce the same result, regardless of the number of times they are called —

rng(1)
r1a = randi(9, 10, 1)                       % First Call

r1a = 10×1

4 7 1 3 2 1 2 4 4 5

r1b = randi(9, 10, 1)                       % Second Call

r1b = 10×1

4 7 2 8 1 7 4 6 2 2

rng(1)
r2 = randi(9, 20, 1)                       % First Call, Length Doubled

r2 = 20×1

4 7 1 3 2 1 2 4 4 5

r2bfr = buffer(r2, 10)                      % Use 'buffer' To See Entire Array

r2bfr = 10×2

4 4 7 7 1 2 3 8 2 1 1 7 2 4 4 6 4 2 5 2

.

[Manu Chaudhary]

data_size = 8; % not necessarily a power-of-2
data_range = [0 255];
data = rng(randi(data_range, data_size, 1) + 1i*randi(data_range, data_size, 1)); % Complex Data

Tried rng but this code is now throwing error? Any way to fix it.

[Star Strider]

The rng call should be entirely separate, and be placed before the first call to the random number generators —

data_size = 8; % not necessarily a power-of-2
data_range = [0 255];
rng(1)
data = randi(data_range, data_size, 1) + 1i*randi(data_range, data_size, 1) % Complex Data

data = 
   1.0e+02 *

   1.0600 + 1.0100i
   1.8400 + 1.3700i
   0.0000 + 1.0700i
   0.7700 + 1.7500i
   0.3700 + 0.5200i
   0.2300 + 2.2400i
   0.4700 + 0.0700i
   0.8800 + 1.7100i

rng(1)
data = randi(data_range, data_size, 1) + 1i*randi(data_range, data_size, 1) % Complex Data

data = 
   1.0e+02 *

   1.0600 + 1.0100i
   1.8400 + 1.3700i
   0.0000 + 1.0700i
   0.7700 + 1.7500i
   0.3700 + 0.5200i
   0.2300 + 2.2400i
   0.4700 + 0.0700i
   0.8800 + 1.7100i

That now runs without error and produces the desired result.

I duplicated the rng call and the ‘data’ assignment to demonstrate that. (The duplicate can be deleted, since I am simply demonstrating the effect here.)

.

[Manu Chaudhary]

Thank you. Great help.

[Star Strider]

As always, my pleasure!