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st: RE: mata (simple): generating random numbers


From   "Steichen, Thomas J." <SteichT@rjrt.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: mata (simple): generating random numbers
Date   Thu, 1 Nov 2007 16:01:16 -0400

Al, there is documentation (help mf_uniform):

help mata uniform()
-----------------------------------------------------------------------------------------------

Title

    [M-5] uniform() -- Uniformly distributed random numbers


Syntax

        real matrix   uniform(real scalar r, real scalar c)

        string scalar uniformseed()

        void          uniformseed(string scalar newseed)

        void          uniformseed(real scalar newseed)


Description

    uniform(r, c) returns an r x c real matrix containing uniformly distributed random
    numbers 0 < element < 1.  uniform() is the same function as Stata's uniform() function.

    uniformseed() returns uniform()'s current seed in encrypted, string form.  uniformseed()
    returns the same thing as Stata's c(seed); see [D] generate and [P] creturn.

    uniformseed(newseed) sets the seed:  a string previously obtained from uniformseed() may
    be specified for the argument, or an integer number may be specified.  uniformseed() has
    the same effect as Stata's set seed command; see [D] generate.


Conformability

    uniform(r, c):
                r:  1 x 1
                c:  1 x 1
           result:  r x c

    uniformseed():
           result:  1 x 1

    uniformseed(newseed):
          newseed:  1 x 1
           result:  void


Diagnostics

    uniform(r, c) aborts with error if r<0 or c<0.

    uniformseed(seed) aborts with error if a string seed is specified and it is malformed
    (was not obtained from uniformseed()).


Source code

    Functions are built in.


Also see

    Manual:  [M-5] uniform()

    Online:  [M-4] standard, [M-4] statistical 



-----------------------------------
Thomas J. Steichen
steicht@rjrt.com
-----------------------------------
 
-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Feiveson, Alan H. (JSC-SK311)
Sent: Thursday, November 01, 2007 3:47 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: mata (simple): generating random numbers

Hi -I've been frustrated by trying to simply generate random uniforms
using uniform()in Mata: Here's what happens:

.. mata
------------------------------------------------- mata (type end to
exit) ---------------------------
: A = 1..5

: E=exp(A)

: A
       1   2   3   4   5
    +---------------------+
  1 |  1   2   3   4   5  |
    +---------------------+

: E
                 1             2             3             4
5
 
+-----------------------------------------------------------------------
+
  1 |  2.718281828   7.389056099   20.08553692   54.59815003
148.4131591  |
 
+-----------------------------------------------------------------------
+

: F=normal(A)

: F
                 1             2             3             4
5
 
+-----------------------------------------------------------------------
+
  1 |  .8413447461   .9772498681    .998650102   .9999683288
..9999997133  |
 
+-----------------------------------------------------------------------
+

: U=uniform()
wrong number of arguments for uniform()
r(3000);

: U=uniform():*1
wrong number of arguments for uniform()
r(3000);

: U=uniform():*A
wrong number of arguments for uniform()
r(3000);

What am I doing wrong? Also, nowhere in the Mata manuals can I find
anything about what arguments the statistical functions take. After
going to interactive  "help', I finally found out they were the same as
the Stata function arguments. So if that's true, why doesn't "uniform()"
work?

Al Feiveson

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