MATLAB: How to create an array of size (x by y ) of normally distributed numbers having a range [a , b]

arraymeanrandomrandom number generator

x = randi(20,5,7)

This randi func is used for uniformly distributed numbers. And for normally distributed numbers randn should be used.

But the randn func only takes the dimensions of the array which we want to create. I am a beginner. So I am stuck in the very basics.

Also I do not have mean and standard deviation values.

Best Answer

If you have the mean and standard deviation, then:

sd = 5;
mu = 500;
X = sd.*randn([x,y]) + mu;

Related Solutions

MATLAB: How to generate only four normally distributed random numbers with given mean and std. deviation

That's statistics, it only works properly if the sample size is large enough.

With two constraints (mean, and std) only two out of your four numbers are truly random. If you really wanted to, you could generate two random numbers and then solve for the last two:

%generate two random numbers: a,b
%a+b+x+y = 4*mu  %definition of mean, x and y unknown.
%gives: y = (4*mu-a-b) - x (eq. 1)
%(a-mu)^2 + (b-mu)^2 + (x-mu)^2 + (y-mu)^2  = 3*sigma^2 %one of the definition of std, (eq.2)
%substitute y from eq. 1 in eq. 2 and solve quadratic equation for x

MATLAB: Normally distributed demand data

You can use the randn function to generate random numbers.

n=300;%number of cases
minval=0;%lowest allowed integer
maxval=1000;%highest allowed integer
mu=50;%median value of distribution
sd=50;%standard deviation of distribution
data=floor(mu+sd*randn(n,1));%round down to integers
invalid= data<minval | data>maxval;
while any(invalid)
    %replace invalid values with newly generated values
    %this will bias the distribution
    data(invalid)=floor(mu+sd*randn(sum(invalid),1));
    invalid= data<minval | data>maxval;
end

Best Answer

Related Solutions

MATLAB: How to generate only four normally distributed random numbers with given mean and std. deviation

MATLAB: Normally distributed demand data

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