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CALL RANTBL

Category:

Random Number

Arguments

seed

is the seed value. For more information about seeds, see Seed Values. A new value for seed is returned each time CALL RANTBL is executed.

Range:	seed < 231 - 1
Note:	If seed 0, the time of day is used to initialize the seed stream.

p_i

is a numeric SAS value.

Range:

0 pi 1 for 0< i n

x

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

Details

The CALL RANTBL routine updates seed and returns a variate x generated from the probability mass function defined by p₁ through p_n.

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.

An inverse transform method applied to a RANUNI uniform variate is used. The CALL RANTBL routine returns these data:

If, for some index j<n,

RANTBL returns only the indices 1 through j, with the probability of occurrence of the index j equal to

Comparisons

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

Examples

This example uses the CALL RANTBL routine:

options nodate pageno=1 linesize=80 pagesize=60;  

data case;
    retain Seed_1 Seed_2 Seed_3 45;
    input p1-p9;
    do i=1 to 10;
       call rantbl(Seed_1,of p1-p9,X1);
       call rantbl(Seed_2,of p1-p9,X2);
       X3=rantbl(Seed_3,of p1-p9);
       if i=5 then
          do;
             Seed_2=18;
             Seed_3=18;
          end;
       output;
    end;
    datalines;
.02 .04 .06 .08 .1 .12 .14 .16 .18
;

proc print;
   id i;
   var Seed_1-Seed_3 X1-X3;
run;

The RANTBL Example shows the results.

The RANTBL Example

The SAS System 1 i Seed_1 Seed_2 Seed_3 X1 X2 X3 1 694315054 694315054 45 6 6 6 2 1404437564 1404437564 45 8 8 8 3 2130505156 2130505156 45 10 10 10 4 1445125588 1445125588 45 8 8 8 5 1013861398 18 18 7 7 7 6 1326029789 707222751 18 8 6 8 7 932142747 991271755 18 7 7 7 8 1988843719 422705333 18 10 4 10 9 516966271 1437043694 18 5 8 5 10 2137808851 1264538018 18 10 8 10

Changing Seed_2 for the CALL RANTBL statement, when I=5, forces the stream of variates for X2 to deviate from the stream of variates for X1. Changing Seed_3 on the RANTBL function, however, has no effect.

See Also

Function: RANTBL

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Copyright 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.