请教:随机数函数normal

shiyiming

请教：
如何用随机数函数normal(seed)产生均值为100,方差为30的正态随机数1000个？

shiyiming

use [i:ibc5xlui]100+30*normal(seed)[/i:ibc5xlui] for 1000 times.
or [i:ibc5xlui]x=repeat(0,1000,1); call randgen(x, 'normal', 100, 30);[/i:ibc5xlui] in PROC IML

shiyiming

谢谢您的回复.您给的答案是一个比一个专业的吧.
能提供一个call randgen的完整的语句吗?

shiyiming

maybe something like this,
[code:1oe65j9r]
proc iml;
x=repeat(0,1000,1);
call randgen(x, 'normal', 100, 30);
create mydataset from x;
append from x;
quit;
[/code:1oe65j9r]

shiyiming

like this
data a;
             drop i
        do i=1 to 1000;
                x=100+30*normal(seed);
                output;
        end;
run;

shiyiming

urchin and qing12bo, thanks  <!-- s:D --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt=":D" title="Very Happy" /><!-- s:D -->

shiyiming

I think you should change the 30 as sqrt(30), the parameters for the function above is the STD , instead of variance

shiyiming

to horse1:
'the parameters for the function above is the STD , instead of variance'
------------------------------------------------------------------------
Are both STD and variance distribution shape paremeters?
How to pick one for the function when both of them are?  

&quot;CALL RANDGEN( result, distname&lt;, parm1&gt;&lt;, parm2&gt;&lt;, parm3&gt;);
result is a preallocated matrix that is to be filled with random samples from the specified distribution.
distname is the name of the distribution that is to be sampled.
parm1 -3 is a distribution shape parameter. &quot;

shiyiming

No, I means that if you use &quot;100+30*normal(seed)&quot; or &quot;call randgen(x,'normal',100,30)&quot;;  the result you obtain is a set of data with mean=100 and variance=900.

you want to get a dataset with the variance=30, right?

shiyiming

Yes, that's right. I want to get a dataset with the variance=30.
And maybe I should put my question in another way: how do you know &quot;100+30*normal(seed)&quot; or &quot;call randgen(x,'normal',100,30)&quot; results in a set of data with mean=100 and variance=900.

Well, I may just test it  <!-- s:lol: --><img src="{SMILIES_PATH}/icon_lol.gif" alt=":lol:" title="Laughing" /><!-- s:lol: -->