Functions and CALL Routines 
Category:  Random Number 
Syntax  
Arguments  
Details  
Comparisons  
Examples  
See Also 
Syntax 
CALL RANCAU(seed,x); 
is the seed value. A new value for seed is returned each time CALL RANCAU is executed.
Range:  seed < 2^{31}  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 RandomNumber Functions and CALL Routines for more information about seed values 
is a numeric SAS variable. A new value for the random variate x is returned each time CALL RANCAU is executed.
Details 
The CALL RANCAU routine updates seed and returns a variate x that is generated from a Cauchy distribution that has a location parameter of 0 and scale parameter of 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.
An acceptancerejection procedure applied to RANUNI uniform variates is used. If u and v are independent uniform (1/2, 1/2) variables and u^{2}+v^{2} 1/4, then u/v is a Cauchy variate.
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 RANCAU routine gives greater control of the seed and random number streams than does the RANCAU function.
Examples 
options nodate pageno=1 linesize=80 pagesize=60; data case; retain Seed_1 Seed_2 Seed_3 45; do i=1 to 10; call rancau(Seed_1,X1); call rancau(Seed_2,X2); X3=rancau(Seed_3); if i=5 then do; Seed_2=18; Seed_3=18; end; output; end; run; proc print; id i; var Seed_1Seed_3 X1X3; run;
This example uses the CALL RANCAU routine:
options pageno=1 ls=80 ps=64 nodate; data u1(keep=x); seed = 104; do i = 1 to 5; call rancau(seed, X); output; end; call symputx('seed', seed); run; data u2(keep=x); seed = &seed; do i = 1 to 5; call rancau(seed, X); output; end; run; data all; set u1 u2; z = rancau(104); run; proc print label; label x = 'Separate Streams' z = 'Single Stream'; run;
Output from the CALL RANCAU Routine
The SAS System 1 Separate Single Obs Streams Stream 1 0.6780 0.6780 2 0.1712 0.1712 3 1.1372 1.1372 4 0.1478 0.1478 5 16.6536 16.6536 6 0.0747 0.0747 7 0.5872 0.5872 8 1.4713 1.4713 9 0.1792 0.1792 10 0.0473 0.0473
See Also 

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