Functions and CALL Routines

CALL RANNOR Routine

Returns a random variate from a normal distribution.

Category:

Random Number

Syntax
Arguments
Details
Comparisons
Examples
See Also

Syntax

CALL RANNOR(seed,x);

Arguments

seed

is the seed value. A new value for seed is returned each time CALL RANNOR is executed.

Range:	seed < 2³¹ - 1
Note:	If seed 0, the time of day is used to initialize the seed stream.
See:	Seed Values and Comparison of Seed Values in Random-Number Functions and CALL Routines for more information about seed values

x

is a numeric variable. A new value for the random variate x is returned each time CALL RANNOR is executed.

Details

The CALL RANNOR routine updates seed and returns a variate x that is generated from a normal distribution, with mean 0 and variance 1.

By adjusting the seeds, you can force streams of variates to agree or disagree for some or all of the observations in the same, or in subsequent, DATA steps.

The CALL RANNOR routine uses the Box-Muller transformation of RANUNI uniform variates.

For a discussion and example of an effective use of the random number CALL routines, see Starting, Stopping, and Restarting a Stream.

Comparisons

The CALL RANNOR routine gives greater control of the seed and random number streams than does the RANNOR function.

Examples

This example uses the CALL RANNOR routine:

options pageno=1 ls=80 ps=64 nodate;

data u1(keep=x);
   seed = 104;
   do i = 1 to 5;
      call rannor(seed, X); 
      output;
   end;
   call symputx('seed', seed);
run;

data u2(keep=x);
   seed = &seed;
   do i = 1 to 5;
      call rannor(seed, X); 
      output;
   end;
run;

data all;
   set u1 u2;
   z = rannor(104);
run;

proc print label;
   label x = 'Separate Streams' z = 'Single Stream';
run;

Output from the CALL RANNOR Routine

                                 The SAS System                                1

                                 Separate     Single
                          Obs     Streams     Stream

                            1     1.30390     1.30390
                            2     1.03049     1.03049
                            3     0.19491     0.19491
                            4    -0.34987    -0.34987
                            5     1.64273     1.64273
                            6    -1.75842    -1.75842
                            7     0.75080     0.75080
                            8     0.94375     0.94375
                            9     0.02436     0.02436
                           10    -0.97256    -0.97256