how do I fix the seed in the trnd function

Dear all,

I use matlab 2012 and I want to generate values from a student t distribution. I use the function "trnd". HOw can I fix the see in this function

thanks

Answer 1

[Wayne King]

I'm not sure why you want to do that since you can use rng() without using the legacy mode by removing those calls and using rng() instead.

But if you are insisting, then you have to do something like:

rng(sd,'v5uniform')

for calls to rand()

and

rng(sd,'v5normal')

for randn(), where sd is the seed.

You should enter

>>help rng

at the command line and read the documentation linked from

Updating Your Random Number Generator Syntax.

This is all explained there in detail.

[Sabbas]

thank you king.

I tried the following:

initially I had

 rand('state',30 );
 randn('state',80);

then I did

 rng(30,'v5uniform')

 rng(80,'v5normal')

but I do not get equivalent results. why?

thanks

[Wayne King]

I get the following

rand('state',30)
x = rand(10,1)
%%%now using rng
rng(30,'v5uniform')
y = rand(10,1)

Identical

Answer 2

[Walter Roberson]

Use the rng() function before you call trnd()

[Sabbas]

you mean for example

rng(1) trnd(7)

because I get this erro message

Error using rng (line 96) The current random number generator is the legacy generator. This is because you have executed a command such as rand('state',0), which activates MATLAB's legacy random number behavior. You may not use RNG to reseed the legacy random number generator.

Use rng('default') to reinitialize the random number generator to its startup configuration, or call RNG using a specific generator type, such as rng(seed,'twister').

JUst to mention that in my code I fix the seed for rand and randn before using rng()

thanks

[Sabbas]

could someone help?

thanks

Answer 3

[Wayne King]

Don't do that. Don't call rand('state', ) before using rng.

rng seeds the random number generator for you. Remove that from and your code and just use rng() to do the work.

[Sabbas]

ok. Is there a way to keep rand('state',) and fix the random seed for trnd at the same time? because ALL my results are based on rand('state', ) and it is very important for me to keep rand('state', ) and randn('state',) . If I do what you say and remove rand('state,) that would be a disaster.

thanks