How to write function to generate gaussian distribution of normal numbers with specified mean, variance and number of values?

Question

Cai Chin 2020-8-19

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/581891-how-to-write-function-to-generate-gaussian-distribution-of-normal-numbers-with-specified-mean-varia

评论： Cai Chin 2020-8-21

I am using MATLAB R2020a Psychtoolbox on Mac OS. I found the following code here to generate a gaussian distribution of random numbers and used it to write a function to specify the mean, variance, upper and lower limits and number of values, however it doesn't generate the numbers.

function distribution(va, mu, ul, ll, nvals)
multiplier=10;
x = mu + randn(multiplier*nvals,1)*sqrt(va); % Generate sufficient random numbers
idx = (ll <= x) & (x <= ul); % Extract the value in the given range [min max]
while sum(idx)<nvals
    multiplier=multiplier+1;
    x = mu + randn(multiplier*nvals,1)*sqrt(va); % Generate sufficient random numbers
    idx = (ll <= x) & (x <= ul); % Extract the value in the given range [min max]
end
x = x(idx);
x = x(1:nvals); % Extract numbers
end

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Jeff Miller 2020-8-19

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/581891-how-to-write-function-to-generate-gaussian-distribution-of-normal-numbers-with-specified-mean-varia#answer_482435

在 MATLAB Online 中打开

you must return something from your function:

function x = distribution(va, mu, ul, ll, nvals)

3 个评论
显示 1更早的评论隐藏 1更早的评论

Jeff Miller 2020-8-20

在 MATLAB Online 中打开

I'm guessing that with some numbers the code just takes a very long time to run. For example, with mean 0 and variance 1, it would take a long time to find numbers between the bounds of +10 and +11, because those are very low probability. You could speed up your function by keeping the numbers between ll and ul and only generating replacements (inside the loop) for those outside those boundaries.

Better still, you might look into MATLAB's truncated normal distribution objects. These will let you do what you want much more directly, something like

n = makedist('normal','mu',mu,'sigma',sqrt(va))
t = truncate(n,ll,ul)
x = random(t,nvals,1)

Cai Chin 2020-8-21

Thanks so much!

请先登录，再进行评论。

How to write function to generate gaussian distribution of normal numbers with specified mean, variance and number of values?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

采纳的回答

3 个评论
显示 1更早的评论隐藏 1更早的评论

更多回答（0 个）

另请参阅

类别

标签

产品

版本

Community Treasure Hunt

How to write function to generate gaussian distribution of normal numbers with specified mean, variance and number of values?

0 个评论 显示 -2更早的评论隐藏 -2更早的评论

采纳的回答

3 个评论 显示 1更早的评论隐藏 1更早的评论

更多回答（0 个）

另请参阅

类别

标签

产品

版本

Community Treasure Hunt

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

3 个评论
显示 1更早的评论隐藏 1更早的评论