matrix of random distribution

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Chantal Lewis
Chantal Lewis 2020-7-22
评论： Karlyn Jones 2020-7-31
Hello,
How to i create a nxn matrix where each column represents a normal distribution and the values in each colum sum to 100? Thankyou

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Jeff Miller
Jeff Miller 2020-7-23
n = 8; % whatever n you want
sd = 1; % whatever you want for the standard deviation of the normal distribution in each column
total = 100; % the total you want
x = randn(n,n) * sd;
for i=1:n
x(:,i) = x(:,i) - mean(x(:,i)) + total/n;
end
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Bruno Luong
Bruno Luong 2020-7-30
编辑：Bruno Luong 2020-7-30
Those ztable is known as https://en.wikipedia.org/wiki/Normal_distribution#Cumulative_distribution_function can computed in MATLAB as following
ztab = @(z) (erf(z/sqrt(2))+1)/2;
z = (-1:0.1:1)'; % put here whatever the z values you want to compute
zt = ztab(z);
table(z,zt)
It produces this
z zt
____ _______
-1 0.15866
-0.9 0.18406
-0.8 0.21186
-0.7 0.24196
-0.6 0.27425
-0.5 0.30854
-0.4 0.34458
-0.3 0.38209
-0.2 0.42074
-0.1 0.46017
0 0.5
0.1 0.53983
0.2 0.57926
0.3 0.61791
0.4 0.65542
0.5 0.69146
0.6 0.72575
0.7 0.75804
0.8 0.78814
0.9 0.81594
1 0.84134
And here the value of ztab of 4 and 5
>> fprintf('z(4)=%1.16f\n', ztab(4))
z(4)=0.9999683287581669
>> fprintf('z(5)=%1.16f\n', ztab(5))
z(5)=0.9999997133484282
Karlyn Jones
Karlyn Jones 2020-7-31
@bruno luong Thank you so much!

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