what is the use of seed.

9 次查看（过去 30 天）
SANJEEV KUMAR
SANJEEV KUMAR 2011-11-27
(1)
for k=1:3
rand('seed',k);
a=rand(1,5)
end
or (2)
for k=1:3
rand(k);
a=rand(1,5)
end
what is the difference between above two command.

请先登录，再回答此问题。

回答（1 个）

Wayne King
Wayne King 2011-11-27
(1) is seeding the random number generator so that it produces a predictable sequence of "random" numbers.
For example, if you run the following loop again and again
for k = 1:3
rand('seed',k);
a = rand(5,1),
end
you will get the same 3 vectors for the variable, a.
In (2), rand(k) is producing a kxk matrix of uniform random numbers, then producing a 1x5 vector of uniform random numbers. So I'm not sure what the point of (2) is.
  3 个评论
显示 1更早的评论
Walter Roberson
Walter Roberson 2011-11-27
Seeding in a loop is seldom desirable, and can often reduce randomness, and is not an acceptable mechanism for security. There have been successful attacks against systems that used seeding in a loop to try to implement security.
Seeding _before_ a loop can be useful.
Daniel Shub
Daniel Shub 2011-11-28
The 'seed' method is pretty dated at this point.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Creating and Concatenating Matrices 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by